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PROGRAMS

FOR THE

BY TIMOTHY ORR KNIOHT,
PROORAMS BY DARREN LqBATT

No. 1726
$14.95

BASIC PROGRAMS

FOR THE

ATARI

600XL & 800XL

BY TIMOTHY ORR KNIGHT,
PROGRAMS BY DARREN LoBATT

TAB

TAB BOOKS Inc.

BLUE RIDGE SUMMIT PA 17214

To my grandparents, Wiltiam T. and Willie Lee Rucker and
Detos L. and Ruth V. Knight, whose heritage, strength, and
wisdom have enriched my life.

ATARI® is a registered trademark, and 600XL/" 800XU™ and AtariWriter™ are
trademarks of Atari, Inc.

FIRST EDITION

FIRST PRINTING

Printed in the United States of America

Reproduction or publication of the content in any manner, without express
permission of the publisher, is prohibited. No liability is assumed with respect to
the use of the information herein.

Library of Congress Cataloging in Publication Data

Knight, Timothy Orr.

BASIC programs for the ATARI 600XL and 800XL.

Includes index.

1. Atari 600XL (Computer)— Programming. 2. Atari
800XL (Computer) — Programming. 3. Basic (Computer
program language) I. LaBatt, Darren. II. Title.
III. Title: B.A.S.I.C. programs for the Atah six
hundred XL and eight hundred XL.
QA76.8.A82K65 1984 001.64'25 83-24243
ISBN 0-8306-0726-9
ISBN 0-8306-1726-4 (pbk.)

Cover photograph courtesy of Atari, Inc.

Contents

Introduction v

1 Programming with Your ATARI Computer 1

The Format of This Book— The Programs— Using This Book

2 Sound and Music Programs 7

Song Library — Sound Maker— Sound Effects Library-
Music Creator- Using Sounds and Music

3 Educational Software 27

History Quiz— Spelling Tester— French Tutor— States and
Capitals — Learning the Easy Way

4 Math and Your Computer 49

Calculator — Basic Skills Check-Up— Geometry — Length
Converter

5 Graphics Programs for the ATARI 69

Terms You Need to Know— Colorbar— Shapes— Drawer-
Graph

6 Games 85

Guess My Number— Simon Says — Blackjack

7 Creating Your Own Programs 101

The Useful Computer— Getting and Developing the Idea—
Programming— Debugging— Making Programs and Money
with Your ATARI— The Future of Computers

Glossary 116

Index 119

other TAB Books by the Authors

No. 1706 Using and Programming tlie ADAM'", including
Ready-to-Run Programs (by Timothy Orr Knight)
No. 1 71 6 Basic BASIC Programs for the ADAM™

Introduction

This book is designed to help you learn more about your ATARI
600XL or 800LX home computer, provide you with a number of
programs that will be useful to you now or in the near future, and
demonstrate to you how a program evolves from start to finish.
The "method of teaching" in this book, however, is not a descrip-
tion of the BASIC language, nor is it a summary of how BASIC
works and how you may use it. This book is a collection of
programs for your ATARI home computer. By using these pro-
grams, you will learn the things mentioned above.

When you are reading this book, you "participate" by typing
in the program lines as they are shown to you. Before you type a
new program into your ATARI, type NEW followed by (as al-
ways) a press of the <RETURN> key. This will prepare the
computer for your program. Then you can begin reading about
the program, how it was made, and what the lines mean as you
enter them into the machine. When you have finished typing in
the program , you will have a ready-to-run piece of software.You
will also know how that program works.

By the time you reach the end of this book, I hope you will
have accomplished three things:

■ You will have finished typing in all 20 programs contained in
this book, so that you can use them later and perhaps modify
them for your own purposes.

■ You will understand how each of the programs works and how
it was developed into a working piece of software.

■ You will comprehend the method by which a program is made,
from idea to completion.

As you read this book, keep in mind that this should be a
learning experience as well as an entertaining one. You'll soon
discover that these two elements combine to Increase your
experience and your knowledge of the ATARI home computers.

Chapter 1

Programming with
Your ATARI Computer

This is a book designed to help you in a number of ways. First of
all, it is a book full of useful, educational, and entertaining pro-
grams which will be in ready-to-run form once you have pur-
ased this book. In fact, with this book you are also getting a large
numt^er of programs which would normally cost you quite a bit of
money at a software store. Second, this is a book which will help
teach you how to use your ATARI home computer effectively,
since you are the person who will be typing in the programs,
learning about the programs as you type them into the computer,
and running these programs to see the result of your efforts.
And, last, this book is intended to teach you a method of program-
ming and explain how you can make your own programs— and
perhaps even sell them for a profit.

To begin, let's take a look at the setup or format of the
programs and instructions within it. This format is easy to under-
stand and was designed to help programmers at any level,
beginning or more advanced, to understand the contents of this
book.

THE FORMAT OF THIS BOOK

This book centers around the 20 programs it contains. Each
is thoroughly explained; you will find three types of explanations
for each program. First of all, I will explain the purpose of pro-
gram lines as I introduce them to you. Then you should type

them into the computer. Don't use the program until you have
completely finished typing It into the computer, and understand
how it works. Another explanation provided Is the explanation of
the important lines within the program. I will tell you the main sets
of program lines and will briefly describe the purpose of that
group of lines. Finally, I will describe the purpose of each of the
variables in the program.

To illustrate this more clearly, let's assume that I have made
a very simple program for the book, as shown below:

1 0 REM THIS PROGRAM SAYS HELLO TO A PERSON

20 PRINT'HI THERE. WHAT IS YOUR NAME"-

30 INPUT NAMES

40 PRINT'HELLO, ";NAME$

50 GOTO 20

This is an extremely simple program, but it will serve our
purposes for this illustration. Now that I have created this pro-
gram, I would describe it to you in the book in a format that might
look like this:

This is a simple program which you may use to let people
become familiar and feel more at ease with the ATARI home
computer. To begin the program, type in the REMark statement
to state the purpose of the program:

10 REM THIS PROGRAM SAYS HELLO TO A PERSON

Next, the computer will print its greeting and accept input from a
person to find out their name.

20 PRINT HI THERE. WHAT IS YOUR NAME"-
30 INPUT NAMES

Then the computer will greet that person by name and repeat
the whole "welcoming process" by going back to line 20:

40 PRINT HELLO, ";NAME$
50 GOTO 20

You might want to expand on this program by program-
ming the computer to get more information about the person, or

make comments such as "YOU HAVE A NICE NAME" or
'YOUR BIRTHDAY IS LATE IN THE YEAR, ISN'T IT?" based on
the input from the user.

Important Line Numbers in HELLO

10 Tells the purpose of the program

20-30 Greets the person and gets name

40 Greets the person by name

50 Goes back to line 20

Important Variables in HELLO
NAMES Receives the name of the person

From the above example, you can get a good idea as to how
the book is set up. You wili learn how the program was made,
what purpose each of the lines serves, and what purpose the
variables serve. As you might guess, this not only provides you
with a good program, which you can easily understand and
modify for your own purposes, but it is also an excellent and
enjoyable way to learn programming.

THE PROGRAMS

To give you an idea of what you have to look forward to in
this book, here are the 19 other programs, with a brief descrip-
tion of each.

Sounds and Music

Song Library. This is a collection of four songs for your ATARI
to play, including "The Caisson Song," "Frere Jacques," "My
Bonnie," and Chopin's fanfas/e impromptu.

Sound Maker. Using your ATARI'S four voices, you can
create your own sounds with this program.

Sound Effects Library. This program provides a collection of
effects for your ATARI to play, including lasers, alarms, gun-
shots, and spaceship blast-off.

Music Creator. Writing music on your ATARI Is easier with
this program, which allows you to input notes and their lengths.

Education
French Tutor. This is a tutorial program which teaches you

and tests you on a vocabulary of simple French words.

States and Capitals, Learn states and capitals by matching
them in this program, which also finds information for you.

History Quiz. Who was Herodotus? Find out with this pro-
gram, which tests you on various events and people in history.

Spelling Tester. Pick the incorrect spelling of a word from the
possibilities presented by this useful program.

Mathematics

Geometry. Find the answer to 16 kinds of geometry prob-
lems, such as areas of figures and volumes of solids, with this
handy program.

Calculator. Find answers to basic math, trigonometric, and
square root problems using this program, the "computer cal-
culator."

Basic Skills Checkup. Test yourself on addition, subtraction,
and multiplication.

Length Converter. Use this program to convert from metric to
"standard," or from any metric or standard unit to any other
metric or standard unit.

Graphics

Drawer. Use the computer screen as a drawing easel for
your visual creations.

Graph. The computer makes a line graph of data you supply
to the program.

Shapes. This program shows you some of the shapes the
ATARI can make and describes how they were made.

Colorbar. Learn the effects of luminance (brightness) and
hue (color) as you create a wide assortment of colors on the
screen.

Games

Blackjack. Play this classic against the computer.

Guess My Number. This is a simple game which teaches you
a lot about how the computer's random number generator oper-
ates.

Simon Says. Memorize as many colors and sounds as you
can to repeat to the computer.

These programs will get you off to a good start on making
your own programs, and will also provide you with a nice selec-
tion of software to use and enjoy later.

USING THIS BOOK

Using this book by simply typing in the programs and run-
ning them is simple enough (and perfectly all right), since that is
the main point. An extension of this concept, however, is to learn
how to create program ideas and programs yourself. By ex-
amining these programs and discovering how they were
created, you can develop your own system for creating an idea
for a program, developing it into a program, and fixing any
problems ("bugs") in it, so that it can be a useful addition to a
computer system.

While you are studying and typing in these programs, write
down any ideas you might have for your own programs and
begin working on them whenever you feel you are ready. Your
experience with your programs will be a far better teacher than
this book, since an individual is his or her own best teacher.
Nevertheless, I hope this book will get you off to a good start, so
you can begin using your own creativity and logic to make your
computer an extension of your mind.

The ATARI 600XL computer system (courtesy Atari, Inc.)

Chapter 2

Sound and Music Programs

The ATARI 600XL and 800XL home computers (Figs. 2-1 and
2-2) come equipped with four separate voices with which you
can create music and sounds. To do this, you specify in your
programs which voice (sound channel) you want to use, what
sound frequency that channel should produce, and what the
volume of that sound should be. In this chapter we'll examine
and create four different programs which produce sounds and
music, and which let you program different songs and sounds
into your ATARI.

SONG LIBRARY

To help stir your interest in the ATARI'S power to create
sounds and music, here is a program which will play any one of
four different available songs for you. Simply select the song you
want to hear and let it play.

In the program, the ATARI first clears the screen then
displays the different songs which can be played. You are then
allowed to give the computer your choice.

100 GRAPHICS O

105 RESTORE

110 POSITION 9,6

120 PRINT" 1. CAISSON SONG"

130 POSITION 9,7

140 PRINT"2, FRERE JACQUES"

150 POSITION 9,8

160 PRINT"3. FANTASIE IMPROMPTU"

170 POSITION 9,9

180 PRINT"4. MY BONNIE"

190 POSITION 9,10

2U0 PRINT"5. END"

210 PRINT: PRINT: PRINT: INPUT CHOICE

Next, the screen is cleared again and the ATARI goes to the
song you wish to be played or, if you selected the fifth option, the
computer ends the program by going to line 6000.

220 GRAPHICS O

230 ON CHOICE GOTO 1000,2000,3000,4000,6000

At this point in the program, the computer will access one of
the four routines below to play a particular song. Note that the
number of frequency/length combinations (note data) varies,
since the lengths of the songs vary.

1000 FOR L00P1=1 TO 83

1020 READ A,B

1030 SOUND 1, A, 14,15

1040 FOR LN=1 TO B*1.5:NEXT LN

1050 SOUND 1,0,0,0

1060 NEXT LOOPl

1U70 GOTO 100

2000 FOR L00P2=1 TO 83

2Oi0 READ A,B

202O NEXT L00P2

2O30 FOR LOOPl=l TO 64

2040 READ A,B

2U50 SOUND 1, A, 14, 15

2060 FOR LN=1 TO B* 1,7: NEXT LN

2070 SOUND 1,0,0,0

2080 NEXT LOOPl

2n90 GOTO 100

3000 FOR L00P2-1 TO 147

3010 READ A,B

3020 NEXT L00P2

3O30 FOR L00P1=1 TO 61

3040 READ A,B

3050 SOUND 1, A, 14, 15

3060 FOR LN=1 TO B*1.3:NEXT LN

3O70 SOUND 1,0, 0,0

3080 NEXT LOOPl

3U90 GOTO 100

4000 TIMES=0

4010 FOR L00P2=1 TO 208

4020 READ A,B

4O30 NEXT LOOP2

4040 FOR LOOPl =1 TO 60

4045 IF LOOP 1=35 THEN BOSUB 4200

4050 READ A,B

4060 SOUND 1, A, 14, 15

4070 FOR LN=1 TO B* 1.2: NEXT LN

4OS0 SOUND 1,0,0,0

4090 NEXT LOOPl

4100 TIME=TIMES+1

4110 IF TIMES=1 THEN RESTORE: GOTO 4010

4120 GOTO 100

4200 FOR REST=1 TO 70: NEXT REST

4210 RETURN

The data below contains the frequencies and the lengths of
the notes in all of the songs:

5000 DATA 81,50,96,50,81,100,81,50,96,50,81,100
5010 DATA 81,50,96,50,81,75,72,25,81,50,96,50
5020 DATA 81,100,96,50,91,50,81,50,91,100,108,50
5030 DATA 81,50,91,100,108,50,125,300,81,50,96,50
5040 DATA 81,100,81,50,96,50,81,100,81,50,96,50
5050 DATA 81,75,72,25,81,50,96,50,81,100,96,50
5060 DATA 91,50,81,50,91,100,108,50,81,50,91,100
5070 DATA 108,50,125,300,81,50,81,50,63,100,63,100
5080 DATA 81,100,81,50,81,50,72,50,64,50
5090 DATA 63,50,72,50,81,100,63,50,63,100,64,50
5100 DATA 72,50,64,50,63,50,72,50,53,300,81,50
5110 DATA 81,50,63,100,63,100,64,100,72,50,64,50
5120 DATA 63,50,72,50,81,100,96,50,91,50,81,50
5130 DATA 91,100,108,50,81,50,91,100,108,50,125,300
5200 DATA 125,50,108,50,96,50,125,50,126,50,108,50
5210 DATA 96,50,125,50,96,50,91,50,81,100,96,50
5220 DATA 91,50,81,100,81,27,72,27,81,27,91,27
5230 DATA 96,50,125,50,81,27,72,27,81,27,91,27
5240 DATA 96,50,125,50,125,50,162,50,126,100,126,50
5250 DATA 162,50,125,100,91,50,81,50,72,50,91,50
5260 DATA 91,50,81,50,72,50,91,50,72,50,68,50
5270 DATA 62,100,72,50,68,50,62,100,62,27,53,27
5280 DATA 62,27,68,27,72,50,91,50,62,27,53,27
5290 DATA 62,27,68,27,72,50,91,50,91,50,125,50
5300 DATA 91,100,91,50,125,50,91,100
5400 DATA 81,200,72,50,81,50,63,50,53,50,47,200
5410 DATA 40,200,45,100,47,100,53,100,47,50,63,50
5420 DATA 81,400,72,200,68,50,72,50,53,50,47,50

5430 DATA 45 , 1 00 ,47,1 00 , 53 , 1 00 , 47 , 1 00 , 63 , 1 00 , 64 , 27
5440 DATA 63,27,53,27,63,27,47,150,53,50,53,400
5450 DATA 81,200,72,50,81,50,63,50,53,50,47,200
5460 DATA 40,200,45,100,47,100,53,100,47,50,63,50
5470 DATA 8 1 , 400 , 72 , 200 , 68 , 50 , 72 , 50 , 53 , 50 , 47 , 50
5480 DATA 45,100,47,100,53,100,47,100,63,100,64,27
5490 DATA 63,27,53,27,63,27,47,150,53,50,53,200,63,200
5500 DATA 108,50,64,75,72,25,81,50,72,50,81,20
5510 DATA 96,50,108,50,128,200,108,50,64,75,72,25
5520 DATA 81,50,81,50,85,50,^1,50,72,250,108,50
5530 DATA 64,75,72,25,81,50,72,50,81,50,96,50
5540 DATA 108,50,128,200,108,50,96,50,72,50,81,50
5550 DATA 85,50,96,50,85,50,81,250,108,150,81,150
5560 DATA 96,150,72,100,81,50,85,50,85,50,85,50
5570 DATA 85,50,96,50,85,50,81,100,72,50,64,150
5580 DATA 108,150,81,150,96,150,72,100,81,50,85,50
5590 DATA 85,50,85,50,85,50,96,50,85,50,81,200

Finally, line 6000 clears the screen and lets the program
end.

6000 GRAPHICS O

In order to add your own songs to this program, add a new
option to the menu, compensate for your addition in line 230 (the
ON . . . GOTO statement), put in new program lines to read and
play the song, and add the DATA statements for the frequencies
and the lengths of the notes in your song.

Important Variables in Song Library

CHOICE Input for choice of song

LOOP1 Reads notes for songs

L00P2 Reads unneeded notes

LN Delay loop for note length

A Note value (period)

B Note length

TIMES Used to play "My Bonnie" twice

REST Rest in music

Important Lines in Song Library

100-200 Sets up menu

21 0-230 Gets choice of song

1000-1070 Plays Xaisson Song"

2000-2090 Plays "Frere Jacques"

3000-3090 Plays fantasie impromptu

4000-4210 Plays '"My Bonnie"

5000-5590 Data

6000 Ends program

SOUND MAKER

You have the ability to create unique notes and sounds on
your ATARI; this program will make that task much easier for
you. This program allows you to change the volume and the
frequency of any of the four voices on the ATARI, and you will
hear all of them playing simultaneously. In addition, you will see
a graphic representation of the frequencies on your screen,
along with the volumes and the frequencies printed at the bottom
of the screen.

In order to use this program, use the following commands:

q.w,e,r Increase the frequency of voice 1,2.3, or 4

(respectively) by one relative unit In a range

from 0 to 255.
Q,W.E.R Decrease the frequency of voice 1 ,2,3, or 4

by one unit.
a,s,d.f Increase the frequency of voice 1,2,3, or 4

by ten units.
A,S,D,F Decrease the frequency of voice 1 ,2,3, or 4

by ten units.
z,x,c,v Increase the volume by one relative unit.

Z,X,C,V Decrease the volume by one relative unit.

The first part of the program is used to establish the vari-
12

ables of Sound Maker and to clear the value at location 764 in
memory, the byte at which information from the keyboard is
registered.

lOU GRAPHICS 14

no PI =255: P2=255: P3=255: P4=255

1 20 V 1 =0 : V2=0 : V3=0 : V4=0

t?f) FRKF 764,?Srj

The computer begins monitoring the keyboard. Below are
the IF-THEN statements for increasing or decreasing the fre-
quency of a voice by one.

130 KEY=PEEK(764)

140 IF KEY^47 THEN P1=P1+1:G0T0 1000

150 IF KEY=46 THEN P2=P2+1:G0T0 1000

160 IF KEY=12 THEN P3=P3+1:GGT0 1000

170 IF KEY=4U THEN P4=P4+1:G0T0 1000

ISO IF KEY=111 THEN P1=P1-1:G0T0 1000

190 IF K:EY=110 THEN P2=P2-1:G0T0 1000

200 IF KEY=106 THEN P3=P3-l:GaT0 lOOO

210 IF KEY=104 THEN P4=P4-l:GaT0 1000

Here are the lines which increase or decrease the fre-
quency of a voice by ten.

220 IF KEY=63 THEN PI =P1 +10: GOTO 1000

230 IF KEY=62 THEN P2=P2+10: GOTO 1000

240 IF KEY=58 THEN P3=P3+10: GOTO lOOO

250 IF KEY=56 THEN P4=P4+10: GOTO 1000

260 IF KEY=127 THEN P1=P1-10: GOTO lOOO

2/0 IF KEY=126 THEN P2=P2-10: GOTO 1000

280 IF KEY=122 THEN P3=P3-10: GOTO lOOO

290 IF KEY=120 THEN P4=P4-10: GOTO lOOO

Finally, here are the lines (in addition to line 400) which are

used to increase or decrease the volume of a voice. These make
the computer go back to line 130 to repeat the "keyboard scan-
ning" process.

300 IF KEY=23 THEN V1=V1+1:G0T0 1000

310 IF KEY-22 THEN V2=V2+1:G0T0 1000

320 IF KEY=18 THEN V3=V3+1:G0T0 1000

330 IF KEY=16 THEN V4=V4+1:G0T0 1000

340 IF KEY=87 THEN Vl=Vl-l;GOTO 1000

350 IF KEY=86 THEN V2=V2-l:GOTO 1000

3^0 IF KEY=82 THEN V3=V3-1:G0T0 1000

370 IF KEY=80 THEN V4=V4-1:G0T0 1000

4n0 GOTO 130

I then programmed the computerto check the values for the
frequencies and volumes of all of the voices to see if any were
^'out of range." If so, the computer would make the proper
correction.

1000 IF Pl>255 THEN PI =255: GOTO 130

1010 IF P2>255 THEN P2=255:G0T0 130

1020 IF P3>255 THEN P3=255:G0T0 130

1030 IF P4>255 THEN P4=255:G0T0 130

iO40 IF Pl<2 THEN P1=2:G0T0 130

1050 IF P2<2 THEN P2-2:G0T0 130

lOhO IF P3<2 THEN P3=2:GOTa 130

1070 IF P4<2 THEN P4=2:G0T0 130

1U80 IF Vl>15 THEN V1=15:60T0 130

1090 IF V2>15 THEN V2=15:G0T0 130

1100 IF V3>15 THEN V3=15:G0T0 130

lUO IF V4>15 THEN V4=15:GOT0 130

1120 IF VKO THEN V 1=0: GOTO 130

1130 IF V2<0 THEN V2=0:60T0 130

1140 IF V3<0 THEN V3=0:GOTO 130
1150 IF V4<0 THEN V4=0:GOTO 130

The ATARI then plays the sounds through all four of its
voices:

2000 SOUND 0,255-Pl,14,Vl
2100 SOUND 1,255-P2,14,V2
2200 SOUND 2,255-P3, 14,V3
2300 SOUND 3,255-P4, 14,V4

Immediately after playing the sounds, the ATARI displays
the graphics representing the frequencies of the sounds.

2500 COLOR O

2510 PLOT 25,0

2520 DRAWTO 25 , (255-Pl > /2

3000 COLOR 1

3010 PLOT 25,159

3020 DRAWTO 25,(255-Pl)/2

3100 COLOR O

3110 PLOT 30,0

3120 DRAWTO 30 , 160- (VI ^ 10)

3200 COLOR 3

3210 PLOT 30,159

3220 DRAWTO 30, 160- (VI * 10)

3300 COLOR O

3310 PLOT 50, O

3320 DRAWTO 50, (255-P2) /2

3400 COLOR 1

3410 PLOT 50,159

3420 DRAWTO 50, (255-P2) /2

3500 COLOR O

35 lO PLOT 55,0

3520 DRAWTO 55 , 1 60- ( V2> 10)

3600 COLOR 3

3610 PLOT 55,159

3620 DRAWTO 55 , 160- ( V2^ 10)

3/0O COLOR 0

37 lO PLOT 85,0

3720 DRAWTO 85 , (255-P3) /2

3800 COLOR 1

3810 PLOT 85, 159

3820 DRAWTO 85 , (255-P3) /2

390O COLOR O

3910 PLOT 90,0

3920 DRAWTO 90 , 160- < V3>10)

4000 COLOR 3

4O10 PLOT 90,159

4020 DRAWTO 90 , 1 60- ( V3 * 1 0 )

410O COLOR O

4110 PLOT 115,0

4120 DRAWTO 1 15, (255-P4) /2

4200 COLOR 1

4210 PLOT 115,159

4220 DRAWTO 1 15, (255-P4> /2

430O COLOR O

4310 PLOT 120,0

4320 DRAWTO 120 , 160- ( V4* lO)

4400 COLOR 3

4410 PLOT 120, 159

4420 DRAWTO 120 , 160- ( V4*10)

Last, the computer shows the values of the frequencies and
the volumes:

4500 PRINT

5000 PRINT 255-Pl,255-P2,255-P3,255-P4

5010 PRINT V1,V2,V3,V4
6000 GOTO 125

Working with this program will produce some interesting
effects. See if you can create certain tones and special sound
effects for your programs by using this utility.

Important Variables in Sound Maker

P1 ,P2,P3,P4 Period values for voices one to four
V1 ,V2,V3,V4 Volumes for voices one to four
KEY Keyboard input

Important Lines in Sound Maker

100-130 Initialization

1 40-400 Sees which key is pressed and adds or

subtracts from voice or period
1 000-1 1 50 Makes sure new values are not out of

range
2000-2300 Plays four sounds

2500-4420 Makes graphs for period and volume of all

four voices
5000-5010 Prints period value and volume value

6000 Goes back to get more keyboard input

SOUND EFFECTS LIBRARY

For some "prepackaged" sounds, here is a selection of
several sound effects. Simply select the one you would like to
hear, and press S when you want to stop listening to the sound.

First, the screen is cleared, the menu is displayed, and your
ATARI lets you Input your choice.

50 GRAPHICS O

100 POSITION 9,6

110 PRINT"SOUND EFFECTS"

120 POSITION 6,9

130 PRINT" 1. LASER FIRE"

140 POSITION 6,10

150 PRINT"2. ALARM"

160 POSITION 6, 11

170 PRINT"3, SPACESHIP THRUST"

180 POSITION 6, 12

190 PR INT "4. REBOUND NOISE"

200 POSITION 6,13

210 PRINT"5. GUN SHOT"

220 POSITION 6,14

230 PRINT"6. RANDOM NOISE"

240 POSITION 6, 15

250 PRINT"/. END"

260 PRINT:PRINT:PRINT"HIT 'S' TO END SOUND"

280 PRINT: PRINT: INPUT CHOICE

Next, the computer goes to the proper line number for your
choice and plays the sound you want to hear.

290 ON CHOICEl GOTO 300,400,500,600,700,800,900

3nO FOR LOaPl=l TO 50

310 SOUND l,L00Pl+5, 14,15

320 NEXT LOOPl

330 SOUND 1,0,0,0

340 FOR WAIT=1 TO 150:NEXT WAIT

350 GOSUB 3000

360 GOTO 300

400 PERI0D=255

410 FOR LOOPl =1 TO 50

420 SOUND 1, PERIOD, 14, 15

425 PER I OD==PER I OD-5

430 NEXT LOOPl

440 SOUND 1 ,0,0,0

450 FOR WAIT^l TO 150: NEXT WAIT

460 GOSUB 3000

470 GOTO 400

500 FOR L00P1=1 TO 100

510 SOUND 1,120,8,15

520 NEXT LOOPl

530 SOUND 1,0,0,0

540 GOSUB 3000

550 GOTO 500

600 V0L=15

610 FOR L00P1=1 TO 15

620 SOUND 1,155, 14, VOL

630 V0L=V0L-1

640 NEXT LOOPl

650 SOUND 1,0,0,0

660 FOR WAIT=1 TO 150:NEXT WAIT

670 GOSUB 3000

680 GOTO 600

700 V0L=15

710 FOR L00P1=1 TO 3

720 SOUND 1,1 50, 8, VOL

730 NEXT LOOPl

735 VOL=7

750 SOUND 1,255,6,V0L-L00P2

760 NEXT L00P2

770 SOUND 1,0,0,0

775 FOR WAIT=1 TO 150:NEXT WAIT

780 GOSUB 3000

790 GOTO 700

800 RN1 = INT (255*RND < 1) +1 )

810 RN2=INT( (28*RND<l)+l)/2)

820 RN3=INT ( 15*RND < 1 ) +1)

830 SOUND 1,RN1,RN2,RN3

840 GOSUB 300O

850 GOTO 800

900 GRAPHICS 0:END

The last part of the program monitors the keyboard for the
"S" key. If it is pressed, the computer stops playing the sound
and returns to the menu. If not, the ATARI keeps on playing.

3000 IF PEEK < 764 )=ib2 THEN POKE 764 ,255: SOUND i, 0,0,0:
GOTO 100
3010 RETURN

Important Variables in Sound Effects Library

CHOICE User's choice of sound

LOOP1 Used to make sounds

WAIT Delay loop

PERIOD The frequency value

VOL Volume

L00P2 Makes sound for second part of gunfire

RN1 Random value for period

RN2 Random value for distortion

RN3 Random value for volume

Important Lines in Sound Effects Library

50-260 Set up menu

280-290 Get choice, go to sound

300-360 Creates laser fire sound

400-470 Creates alarm sound

500-550 Spaceship thrust

600-680 Rebound noise

700-790 Gunshot noise

800-850 Random noise

900 Ends program

3000-3010 Turns off sound and resets the keyboard

MUSIC CREATOR

Not only may you want to create certain sounds on your
computer, you might also want to write music with your ATARI.

fi /=V r-

/Iv

(( )

^ c

SYMBOL

NOTE

VALUE

Whole

4 beats

Half

2 beats

Quarter

1 beat

\
d

Eighth

V2 beat

}

Sixteenth

V'4 beat

F-ig. 2-1 . Musical notes.

The following program will allow you to enter notes and their
lengths, and then chain the notes together to make a song.

Music creator first establishes the variables it is going to
use, shows Its title, and lets you begin inputting your song. To
input a note, type in a four-character code consisting of:

1) A note name from the set A,B,C,D,E,F,G.

2) A blank character if the note is natural, or a sharp sign
( * ) if it is sharp.

3) The octave level, a number from 1 to 3 representing how
■'high" the octave is.

4) The length of the note, which can be S (sixteenth note),
E (eighth), Q (quarter), H (half), or W (whole note).

The notes available, as well as acomparison of theirtime values,
are shown in Fig. 2-1.

50 DIM INP*(5):DIM A* (3)
^0 DIM P<90):DIM L(90)

70 DIM L*(3)

100 GRAPHICS O

110 POSITION 10,4

120 PR I NT "MUSIC CREATOR"

130 NM=1

135 PRINT: PRINT

140 INPUT INP*

This section of the program lets your ATARI accept two
other commands— PLAY, which will play your song, and END,
which will stop the program completely.

150 IF INP*="PLAY" THEN NM=NM-1:G0T0 lOOO
160 IF INP*="END" THEN GRAPHICS OrEND

At this point, the computer will compare your note with the
notes in the DATA statements at the end of the program to find
out the frequency of the note you selected.

170 READ A*,B,C

200 IF A*=INP*(1,2) THEN 300

210 GOTO 150

300 D=VAL(INP*(3,3) )

310 IF BOD THEN GOTO 150

^O P(NM)=C

500 L*=INP*(4,4)

Then your ATARI determines the length of the note you
selected:

510 IF LS="S" THEN L=25

520 IF L^="E" THEN L=50

530 IF LS="Q" THEN L=100

540 IF LS="H" THEN L==200

550 IF L*="W" THEN L=400

560 L(NM)=L

To let you know what you have just entered, the connputer
will play the note. It will then go back to the INPUT routine so you
can continue supplying notes until you are ready to PLAY the
song.

600 SOUND 1,P(NM) ,14, 15

610 FOR L00P1 = 1 TO L<NM)!NEXT LC30P1

620 SOUND 1,0,0,0

700 NM=NM+1

710 RESTORE

720 GOTO 140

When you are ready to play the song, this routine will do just
that.

1000 FOR L00P2=1 TO NM

1010 SOUND 1,P<L00P2) ,14,15

1020 FOR L00P3=1 TO L (L00P2) : NEXT L00P3

1030 NEXT L00P2

2000 BOUND 1 ,0,0,0

2010 NM=NM+1

2020 GOTO 140

Here, at last, is the data for the notes you might use in the
program:

5000 DATA C , 1 ,251 ,C# , 1 , 230,D ,1,217
5010 DATA D#,1,204,E ,1,193,F ,1,182
5020 DATA F#, 1,173,6 , 1 , 162,G#, 1 , 153
5030 DATA A , 1 , 144, A#, 1 , 136,B ,1,128
5040 DATA C , 2, 126 ,C#,2, 1 14,D, 2, IDS
5050 DATA D#,2,102,E ,2,96,F ,2,91
5060 DATA F#,2,85,G , 2,81 ,G#,2, 76
5070 DATA A , 2, 72, A#, 2,68,B ,2,64
5080 DATA C ,3,63,C#,3,57,D ,3,53

5090 DATA D#,3,50,E ,3,47,F ,3,45
5100 DATA F#,3,42,G ,3,40,G#,3,37
5110 DATA A ,3,35,A#,3,33,B ,3,31

See if you can construct a routine to save your songs to the
disk. If you would like to add more songs to the "Song Library"
program earlier in this chapter, add the songs you create with
this program.

Important Variables in Music Creator

INP$ input a note of music

A$ The note frequency

P(X) The period for each note

L(X) The length of each note

L$ The input for the note length

NM Number of the note

B Data for octave number

C Data for frequency value

D Numeric value of octave number

L00P1 Delay loop for making note length

LOOP2 Used for playing song

LOOPS Another delay loop

Important Lines in Music Creator

50-135 initialization

140 Gets input

1 50-1 60 Checks to see if user wants to play song or end

program
170-310 Finds appropriate data

400 Gets period

500-560 Gets note length

600-620 Plays note just input

700-720 Goes to get next note from user

1000-2020 Plays song
5000-5110 Data for notes, octave, and period value

USING SOUNDS AND MUSIC

With four voices available on the ATARI, this computer
certainly is capable of producing complex pieces of music and
interesting, unusual sounds for your programs. Add as many
sounds as you can to your games and utilize songs and sounds

in educational programs. You'll probably find that creating these
is one of the most entertaining aspects of programming your
ATARI computer.

7^76 ATARI 800XL computer system (courtesy Atari, Inc.)

Chapter 3

Educational Software

Computers are often said to be one of the best tools available for
education. This may well be true, because computers are the
most patient teachers you could ever find. They can remember
large amounts of data, recite it accurately, and accept input from
any number of students as many times as needed. Computers
don't have some of the "human" qualities that real teachers do,
but they are excellent at the kinds of work which are repetitive
and probably bonng for people. Moreover, the student can con-
tinue to work with a program until he or she memorizes the
information presented by the computer.

In this chapter we'll be looking at four different programs
which focus on education. You can easily expand and modify
these programs for your own use and for the academic level for
the people using the programs. However, these programs are
fully functional as they now exist; you are sure to learn some-
thing from using these programs-not only about history or
French or geography or spelling, but also about programming
your ATARI home computer.

HISTORY QUIZ

This program utilizes a large quantity of data by randomly
selecting several pieces of information which relate to history.
Then it asks you which one particular part of history is usually
^elated to another part. With this program, the computer can

teach you more about history by quizzing you on a variety of
subjects and letting you learn by trial and error.

The first part of the progrann sets up the variables and clears
the screen.

10 DIM A* (30): DIM Ei*(30)

20 DIM C^ (30): DIM D*<30)

30 DIM E*<n :DIM Ft^ ( 1 )

40 DIM ANSWER* (30)

50 SC=0:TIMES=0

100 GRAPHICS 0

The ATARI waits until you are ready to begin and then
clears the screen once nnore:

no POSITION 12,4

120 FRINT"HISTORY QUIZ"

130 POSITION 7,8

140 PRINT"HIT ANY KEY TO CONTINUE"

150 INPUT E*

200 GRAPHICS 0

At this point the conriputer reads the data from the end of the
progrann and selects a random number from 1 to 6. This random
number will determine the order in which the aspects of history
will be printed— so you'll never know which person or event is
associated with another person or event until you are familiar
with the facts in this program.

205 TIMES=TIMES+1

210 READ A:t,B*,C:$,D*

220 POSITION 7,4

230 PRINT AS

240 POSITION 7,6

250 PRINT" IS MOST ASSOCIATED WITHs"

300 RAN=INT (6*RND ( 1 ) +1 )

305 POSITION 2, 10

The computer then prints out the data and goes to the
routine at line 700, which will accept your input.

310 IF RAN==1 THEN 400

320 IF RAN=2 THEN 450

330 IF RAN=3 THEN 500

340 IF RAN=4 THEN 550

350 IF RAN=5 THEN 600

360 IF RAN=6 THEN 650

400 PRINT B*

410 PRINT C*

420 PRINT D*

430 GOTO 700

450 PRINT C*

460 PRINT B*

470 PRINT D*

480 GOTO 700

SOO PRINT D*

510 PRINT C»

520 PRINT B*

530 GOTO 700

550 PRINT B*

560 PRINT D*

570 PRINT C*

580 GOTO 780

600 PRINT C*

610 PRINT D*

620 PRINT B*

630 GOTO 700

650 PRINT D*

660 PRINT B*

670 PRINT C*
680 GOTO 700

Here the computer accepts your input and checks to see if it
is correct or not. Then the ATARI asks if you would like to
continue with another question.

700 POSITION 7,15

710 INPUT ANSWER*

720 IF ANSWER^OBt THEN 800

730 PRINT: PRINT"CORRECT"

740 SC-SC+1

750 GOTO 900

800 PRINT: PRINT" INCORRECT - THE RIGHT ANSWER IS " ; B*

810 GOTO 900

900 IF TIMES=22 THEN 2000

910 PRINT"DO YOU WANT TO CONTINUE-^"

920 INPUT F*

930 IF F:|:="Y" THEN 200

Finally, here are the data for the program. Remember not to
put any extra spaces in the data, since that might make the
program malfunction.

1000 DATA HERODOTUS, FATHER OF HISTORY , TROJAN WAR, ATTACK

ON ROME

1010 DATA WATERLOO, NAPOLEON, LORD NELSON, DUKE OF WELLINGTON

1020 DATA ANTIETAM, CIVIL WAR , GREECE , WORLD WAR II

1030 DATA HOMER, POETRY, SUBMARINE, JET PLANE

1040 DATA HENRY FORD , INDUSTRIAL 1ST , PRESIDENT , FAMOUS
HISTORIAN

1050 DATA HANNIBAL, ELEPHANTS, BABYLON, PEOPLE EATERS
1060 DATA HAMMURABI, BABYLON, ELEPHANTS, HARDWARE
1070 DATA KING JOHN, MAGNA CARTA , ENGLISH CIVIL WAR,
FOUGHT DUKE OF NORMANDY

1080 DATA KIT CARSON, WEST , NORTH , SOUTH

1090 DATA SHERMAN, NORTH, WEST, SOUTH

1100 DATA JEB STUART, SOUTH, NORTH, WEST

lUO DATA SAMUEL ADAMS, AMERICAN REVOLUTION, FAMOUS

ECONOMIST, SECOND PRESIDENT

1120 DATA GIBRALTAR, LORD NELSON, DUKE OF WELLINGTON,
NAPOLEON

1130 DATA U.S. SENATE, TRUMAN, JACKSON, EISENHOWER
1140 DATA THOMAS EDISON , MOTION PICTURES , TYPEWRITER,
AIRPLANES

1150 DATA PRINTING, GUTENBERG, LINDERBERG, HEGEL

1160 DATA WILLIAM THE CONQUERER, 1066 , ROME , 1512

1170 DATA KARL MARX , HEGEL , ADAM SMITH, DARWIN

1180 DATA CARTHAGE, ROME, TURKEY, ENGLAND

1190 DATA RENOIR, PAINTER, PHILOSOPHER, INDUSTRIALIST

1200 DATA SHAKESPEARE, ELIZABETH I, KING JOHN, HENRY VIII

1210 DATA JOHN PAUL JONES , AMERICAN REVOLUTION , WAR OF

1812, POET

2000 PR I NT: PR I NT "YOUR SCORE IS " ; INT ( (SC/TIMES) *100) ; "
PERCENT. "

Line 2000, shown above, is the final line In the program. It
computes your score by dividing the number of your correct
answers by the total number of questions asked, and then multi-
plying that fraction by 100 to get the percentage.

Important Variables in History Quiz

A$ First word

B$,C$,D$ Words with which to associate the first word

E$, F$ Input needed to continue

ANSWERS Player's response for quiz

SC Score

TIMES Number of questions asked

RAN Random number

Important Lines in History Quiz

10-50 Initialization

100-150 Introduction

200-250 Beginning of quiz

300-680 Sets up three words in random order

700-810 Gets responses and sees if it's correct

900-930 Sees if player wants to continue

1000-1210 Data

2000 Computes player's score

SPELLING TESTER

If you have trouble with your spelling, as most of us do, or
you know someone who could use help, here is a program which
will display incorrect and correct spellings of words as shown in
Fig. 3-1. You decide which is correct.

The program begins by DIMensioning the variables and
clearing the screen:

10 DIM A.r (15) :DIM B*(15)
20 DIM I NPS( 15): DIM YN:f ( 1 )

30 SC=0

EDITER
EDITOR

WHICH IS SPELLED CORRECTLy^
? EDITOR

CORRECT

DO YOU WANT TO CONTINUE ?

Fig. 3-1. Sample screen for Spelling Checker.
32

Your ATARI then begins reading the words, displaying the
incorrectly and correctly spelled versions in a random order,
asking you which one is spelled correctly.

100 FOR LaOPl=l TO 37

110 GRAPHICS 0

120 READ A^,B-^

130 RAN=INT(2>-RND(1)+1)

140 IF RAN=1 THEN 200

150 PR I NT: PR I NT: PR I NT A*

160 PRINT BS-

170 GOTO 300

200 PR I NT: PR I NT: PR I NT B*

210 PRINT (^S-

300 PR I NT: PR I NT "WHICH IS SPELLED CORRECTLY"

310 INPUT INP:$:

Once you give an answer, the computer checks to see if you
are right or wrong, and also asks if you would like to continue
using the program. If not, it will tell you what your score is.

320 IF INPit-A* THEN SC^SC+1 : PRINT: PRINT"CORRECT. " :

GOTO 500

330 PRINT: PRINT"WRONG- "

500 PRINT; PR I NT "DO YOU WANT TO CONTINUE?"

510 INPUT YN:|:

520 IF YN:t="N" THEN 600

530 NEXT LOOP!

600 PRINT: PR I NT "YOUR SCORE IS " ; INT ( (SC/LOOPl ) *100) ; "

PERCENT. "

Here, at the end of the program, are the data:

2000 DATA IMPERIL, I nPER ILL, SHAPELY, SHAPLY, SENSORY,
SENSERY

2010 DATA HARASS,HARRASS,iriMINENCE,EMMINENCE,II1PALPABLE,

IMPALPIBLE

2020 DATA IMPELLING , IMPELING , PERSISTENT , PERSISTANT ,

PROFESSOR, PROFESOR

2030 DATA SUCCEED , SUCCEDE , TOMOROW, TOMMOROW , DISTILL ,
DISTIL

2040 DATA BLURRED, BLURED , BOGUS , BOGOS , AROUSE , ARROUSE
2050 DATA HIJACKER , HIGH- J ACKER , HARD-CORE ,HARDCORE ,
HALFBACK , HALF-BACK

2060 DATA GRITTY , GR I TY , GUARANTEE , GUARRANTEE , GROVEL ,
GROVELL

2070 DATA ENSUE , INSUE , HIGHLIGHT , HIGH-LIGHT , FOSSIL ,
FOSSLE

2080 DATA MISSILE , MISSLE , FULFILL , FULLFIL , ELECTORATE ,

ELLECTORATE

2090 DATA EDITOR , ED ITER , ELUDE ,ELLUDE , DEFER , DEFFER

2100 DATA CONTROL, CONTROLL, CONTROLLED, CONTROLED,

STOPPIWC, ST0PIN6

2110 DATA MARSHMALLOW,MARSHMELLOW, HYGIENE, HUGENE
2120 DATA FLOTSAM, FLOTSOM, ADVANTAGEOUS, ADVANTAGOUS

You might want to try adding words of your own to the
program. Simply put in new DATA statements and adjust the
FOR/NEXT loop near the beginning of the program so it can
accommodate any extra words.

Important Variables in Spelling Tester

A$ Data for the correct spelling

B$ Data for incorrect spelling

SC Score correct

L00P1 Quiz

RAN Random number (1 or 2)

INP$ User's answer

Important Lines in Spelling Tester

10-30 Initialization

100 Beginning of quiz

120 Reads two words from data

130-210 Prints the words in random order

300-330 Asks for answer, sees If it is correct

500-530 Sees if player wants to continue

600 Computers player's score

2000-2120 Data

FRENCH TUTOR

If you are interested in the French language, or if you'd just
like to learn a few words to use at your favorite international
restaurant, this program will not only teach you French words but
also test you on them. Again, you can add more words to the
DATA statements, but you should also alter the program to
account for the added words.

As usual, the first part of the program sets up the variables
and clears the screen:

10 DIM E*:(15) :DIM F*(15)

20 DIM INP*:C15) :DIM YN«: ( 1 >

30 SC-0

100 GRAPHICS 0

Then a "menu" is displayed from which you may select an
option. The "parts" are the lessons from which you may learn
certain words, and the "test" will quiz you on those words.

110 POSITION 10,5

120 PRINT"FRENCH LESSON"

130 POSITION 7, 10

140 PRINT"!, PART ONE"

150 POSITION 7, 11

160 PRINT"2. PART TWO"

170 POSITION 7, 12

180 PR INT" 3. PART THREE"

190 POSITION 7,13

200 PRINT"4, PART FOUR"

210 POSITION 7,14

220 PRINT"5, PART FIVE"

230 POSITION 7,15

240 PRINT"6. PART SIX"

250 POSITION 7, 16

260 PRINT"7, TEST"

270 INPUT CH

280 ON CH GOTO 500,300,320,340,360,300,1000

Once you have selected an option, the computer will go to a
different part of the program so it may either teach you or quiz
you on the words:

300 CLEAR=13

310 GOTO 400

320 CLEAR=26

330 GOTO 400

340 CLEAR«=39

350 GOTO 400

360 CLEAR=52

370 GOTO 400

380 CLEAR»=65

400 FOR L00P1=1 TO CLEAR

410 READ F*,E*

420 NEXT LOOPl

500 GRAPHICS 0

510 FOR L00P2=i TO 13

520 READ F*,E:*

530 PRINT FS

540 PRINT" ";E*

550 NEXT L00P2

600 PRINT:PRINT:PRINT'*HIT ANY KEY TO CONTINUE"

610 INPUT lNP-$-

620 RESTORE

630 GOTO 100

If you do "take the test" you will have to put in the French
word for each English word, using the dialogue shown in Fig.
3-2. The ATARI will keep track of your score as you go.

1000 FOR L00P3=1 TO 78

1010 GRAPHICS 0

1020 READ FS,E$

1030 PRINTS PRINT E*

1040 PRINT: PRINT"WHAT IS THE FRENCH WORD?"

1050 PRINT" (INCLUDE THE ARTICLE)"

1060 INPUT INP:^

1070 IF INP*<>F* THEN 1100

1080 GOTO 1200

GOOD EVENING

WHAT IS THE FRENCH WORD '?

(INCLUDE THE ARTICLE)
? BONSOIR

CORRECT

Fig. 3-2. Taking the French test.

1100 PRINTtPRINT"WRONG"
1120 GOTO 1500
1200 PRINT: PRINT*'CORRECT"
1210 SC=SC+1

If you want to continue the program, you may do so when
the computer asks you:

1500 PRINT: PR I NT "DO YOU WANT TO CONTINUE?"

1510 INPUT YN«

1520 IF YN«<>"Y" THEN 1600

1530 NEXT L0OP3

Finally, the computer tells you your score based on how well
you did on the test.

1600 PRINT: PRINT" YOUR SCORE IS " ; INT < (SC/L00P3) *100) j "

PERCENT, "

The data are located at the end of the program.

2000 DATA L ' ADDI T ION, B ILL, L'AGNEAU, LAMB

2010 DATA L' AIDE, ASS I STANCE, L'APRES-MIDI, AFTERNOON

2020 DATA L ' AUTOBUS , BUS , LE BAIN, BATH

2030 DATA LE BETE , BEAST , LA BL ANCH I SSER IE, LAUNDRY

2040 DATA LE BONBON , CANDY , BONJOUR , HELLO

2050 DATA BONSOIR,GOOD EVENING, LA BOUL ANGER IE, BAKERY

2060 DATA LA BOUTIQUE , SHOP, LA CAB I NE, CAB IN

2070 DATA LE CAMION , TRUCK ,LE CHASSEUR , BELLBOY

2080 DATA LE CHAUSSURE , SHOE , LE CHEQUE, CHECK

2090 DATA LE CHIEN,DOG,LE COMPLET,SUIT

2100 DATA LA CRAVATE , NECKTIE , LE CUIT, LEATHER

2110 DATA DE,FROM,DEMAIN,TOMMOROW

2120 DATA LA DOUANE , CUSTOMS , LE DRAPE AU, FLAG

2130 DATA L' ESSENCE, GASOLINE, LA FEMME, WOMAN

2140 DATA LE GARCON , WAITER , LA GARE, STATION

2150 DATA LE GENDARME , POLICEMAN , LA GLACE, ICE CREAM

2160 DATA GR ATU IT, FREE, L' MORA I RE, SCHEDULE

2170 DATA L'HOROLOGE,CLOCK,L 'HOTELIER, INNKEEPER

2180 DATA L'IMPOT, TAX, INTERDIT, FORBIDDEN

2190 DATA LUND I, MONDAY,MARD I, TUESDAY

2200 DATA MERCREDI , WEDNESDAY, JEUDI , THURSDAY

2210 DATA VENDREDI, FRIDAY, SAMEDI, SATURDAY

2220 DATA DIMANCHE , SUNDAY , LE JOUET,TQY

2230 DATA LE JOUR, DAY, LE JOURNAL , NEWSPAPER

2240 DATA LE LIBRAIRIE , BOOKSTORE ,LA MAIRIE,TOWN HALL

2250 DATA LE MATIN, MORNING , LE MEDEC IN , DOCTOR

2260 DATA MERCI, THANK YOU , LE METRO , SUBWAY

2270 DATA LE MIDI, NOON, LE MINUIT , MIDNIGHT

2280 DATA LE MOIS, MONTH ,L ' OEUF , EGG

2290 DATA LE PAIN , BREAD , PERDU , LOST

2300 DATA LE PERE , FATHER , LE PLAN, CITY MAP

2310 DATA LE POISSON , FISH , LE PORTEUR , PORTER

2320 DATA LE POULET , CHICKEN , LE QUART I ER , NEIGHBORHOOD

2330 DATA LE REVEIL,ALARM CLOCK , LA ROBE, DRESS

2340 DATA LE SAC, BAG, LA SALLE, ROOM

2350 DATA LA SEMAINE, WEEK, LA SERVEUSE, WAITRESS

2360 DATA LE STYLO, PEN, LA TAILLE,SIZE

2370 DATA LE TAILLEUR, TAILOR, LA VAL I SE , SUITCASE

2380 DATA LA VI ANDE , MEAT , LA VOITURE,CAR

If you would like to learn a language other than French, you
can use the same technique in this program. Simply include the
data for the English and the foreign-language words.

Important Variables in French Tutor

E$ English word in data

F$ French word in data

fNP$ Player's response to test

YN$ Used to ask if player wants to continue

SC Score in quiz

CH Choice from menu (input)

CLEAR Number of words and definitions in data to skip

over

LOOP1 Used to do the above

LOOP2 Used to read data and print information on

screen

L00P3 Used to ask questions for test

Important Lines in French Tutor

10-30 Initialization

100-260 Sets up menu

270-280 Goes to selected item

300-380 Sets number of pairs of data to skip over

400-420 Does the above

500-550 Reads desired data, prints it out

600-630 Goes back to menu

1000 Beginning of test

1010-1050 Asks question

1 060-1 080 Gets response

1 100-1210 Tells player if he's right or wrong

1500-1530 Asks player if he wants to continue

1 600 Computes player's score

STATES AND CAPITALS

At some time in every American's life he or she must learn
the states and capitals. As terrible as this task may be, the
computer can make it more bearable for you, as you will discover
with this program.

First the computer sets up the program and gives you the
option of taking a quiz on the states and their capitals, or simply
finding information about which state has what capital, or vice
versa.

5 DIM A*<50):DIM B*(50)

6 DIM INP*(20):DIM USED (50)

7 DIM RESP0NSE«:C2O) sDIN YN* ( 1 )
10 GRAPHICS 0

20 POSITION 9,4

30 PR I NT "STATES AND CAPITALS MENU"

40 POSITION 7,7

50 PR I NT " 1 . I NFQRMAT I ON "

60 POSITION 7,9

70 PRINT"2, QUIZ"

80 POSITION 7,14

90 PR I NT "PLEASE CHOOSE ONE."

95 POSITION 7,16

100 INPUT CH

110 IF CH>2 THEN SO

130 IF CH=1 THEN 150

140 IF CH=2 THEN 1000

If you want information, you simply tell the computer that
you want to find out which state belongs to what capital or which
capital belongs to what state. (See Fig. 3-3.) Once you have
done this, the computer will find the information.

150 GRAPHICS 0
160 POSITION 7,7

1 YOU NAME THE STATE AND THE COMPUTER
WILL FIND THE CAPITAL

2. YOU NAME THE CAPITAL AND THE COMPUTER
WILL FIND THE STATE

^ 1

WHAT IS THE STATE^

^ LOUISIANA

THE CAPITAL OF LOUISIANA IS BATON ROUGE

Fig. 3-3. Getting information from States and Capitals.

170 PRINT"! . YOU NAME THE STATE AND THE COMPUTER WILL

FIND THE CAPITAL. "

180 POSITION 7,10

190 PRINT'*2, YOU NAME THE CAPITAL AND THE COMPUTER WILL

FIND THE STATE. "

200 POSITION 7,15

205 PRINT"PLEASE INPUT YOUR CHOICE";

210 INPUT CH2

220 ON CH2 GOTO 240,400

230 GOTO 200

240 GRAPHICS 0

250 POSITION 7,7

260 PRINT"WHAT IS THE STATE?"

270 INPUT INP*

280 FOR Li=l TO 50

290 READ A*,B*

300 IF A#«INP* THEN 320

310 NEXT LI

315 IF Ll=51 THEN PRINT" INVALID INPUT": SOTO 260

320 POSITION 7, 11

330 PRINT"THE CAPITAL OF "jiA*;" IS " j B*

340 FOR DELAY"! TO 750iNEXT DELAY

345 RESTORE

350 GOTO 10

400 GRAPHICS O

410 POSITION 7,7

420 PR I NT "WHAT IS THE CAPITAL?

430 INPUT INP*

440 FOR Ll=l TO 50

450 READ A*,B*

460 IF B*=INP* THEN 480

470 NEXT LI

475 IF LI =51 THEN PRINT" INVALID INPUT": GOTO 420

480 POSITION 7,11

490 PRINT B*|" IS THE CAPITAL OF " ; A*

500 GOTO 340

Here are the data of the states and their capitals required by

this program:

800 DATA ALABAMA, MONTGOMERY, ALASKA, JUNEAU

810 DATA ARIZONA, PHOENIX, ARKANSAS, LITTLE ROCK

820 DATA CALIFORNIA, SACRAMENTO, COLORADO, DENVER

830 DATA CONNECTICUT, HARTFORD, DELAWARE, DOVER

840 DATA FLORIDA, TALLAHASEE, GEORGIA, ATLANTA

850 DATA HAWAI I , HONOLULU, IDAHO, BOISE

860 DATA ILLINOIS, SPRINGFIELD, INDIANA, INDIANAPOLIS

870 DATA IOWA,DES MO I NES , KANSAS , TOPEKA

880 DATA KENTUCKY, FRANKFORT, LOU I SI ANA, BATON ROUGE

890 DATA MAINE, AUGUSTA, MARYLAND, ANNAPOLIS

900 DATA MASSACHUSETTS, BOSTON, MICHIGAN, LANSING

910 DATA MINNESOTA, ST. PAUL , M I SS I SS I PP I , J ACKSON

920 DATA MISSOURI , JEFFERSON C I TY , MONTANA , HELENA

930 DATA NEBRASKA, LINCOLN, NEVADA, CARSON CITY

940 DATA NEW HAMPSH I RE , CONCORD , NEW JERSEY , TRENTON

950 DATA NEW MEXICO, SANTA FE , NEW YORK, ALBANY

960 DATA NORTH CAROL I NA , RALE I GH , NORTH DAKOTA , BI SMARK

970 DATA OHIO, COLUMBUS, OKLAHOMA, OKLAHOMA CITY

980 DATA OREGON, SALEM, PENNSYLVANIA, PHILADELPHIA

990 DATA RHODE I SLAND , PROVI DENCE , SOUTH CAROLINDA,

COLUMBIA

992 DATA SOUTH DAKOTA , PIERRE , TENNESSEE , NASHVILLE

993 DATA TEXAS , AUSTIN , UTAH , SALT LAKE CITY

995 DATA VERMONT , MONTPELIER , VIRGINIA, RICHMOND

997 DATA WASHINGTON ,OLYMPIA , WEST VIRGINIA, CHARLESTON

998 DATA WISCONSIN , MADISON, WYOMINS, CHEYENNE

And, finally, if you want to be tested by the computer, this
part of the program will require you to name either the state of a
capital or the capital of a state, whichever you prefer.

1000 GRAPHICS 0

1003 FOR L5=l TO 50

1005 USED(L5)=0

1007 NEXT L5

1010 POSITION 7,7

1020 PRINT" 1- 'WHAT IS THE CAPITAL?'"

1030 POSITION 7,9

1040 PRINT"2, 'WHAT IS THE STATE?'"

1050 POSITION 7, 12

1060 INPUT CH3

1070 IF CH3=1 THEN 1100

lOaO IF CH3=2 THEN 1100

1090 GOTO 1060

1100 GRAPHICS 0

1105 FOR L2«l TO 50

1110 RAN= ( 50*RND <!)+!)

1120 FOR L3-1 TO 50

1130 IF RAN=USED(L3) THEN 1110

1140 NEXT L3

1150 USED(L2)='RAN

1160 FOR L4=l TO RAN

1170 READ A*,B*

1180 NEXT L4

1190 RESTORE

1200 IF CH3=1 THEN 1300

1210 IF CH3=2 THEN 1400

1300 PRINT-WHAT IS THE CAPITAL OF "jA*;"?"

1310 INPUT RESPONSE*

1320 IF RESPONSE*=B* THEN PRINT"CORRECT" : SC=SC+1 :

GOTO 1500

1330 PRINT"WRONG"

1340 PRINT"THE CAPITAL OF ";A*;" IS " ; B*

1350 GOTO 1500

1400 PRINT B*;" IS THE CAPITAL OF WHAT STATE?"

1410 INPUT RESPONSE*

1420 IF RESPONSE*=A* THEN PRINT"CORRECT" a SC=SC+1 :

GOTO 1500

1430 PRINT"WRONG"

1440 PRINT B*; " IS THE CAPITAL OF " ; A*

1450 GOTO 1500

You can keep answering questions until you are satisfied
that you know the material. Then the computer will give you your
score.

ISOO PRINT"DO YOU WANT TO TRY ANOTHER?*'

1510 INPUT YN*

1520 IF YN*="Y" THEN 1600

1525 GRAPHICS 0

1530 NEXT L2

1600 PRINT" YOUR SCORE IS " 5 INTC <SC/L2) *1003 " PERCENT."

You could use this same program concept to match any two
things, such as International capitals with their respective coun-
tries, of scientific achievements with people who made them
possible, and so on. There are many possibilities in educational
software, and you can probably come up with an excellent
subject that a person could learn with the help of the ATARI.

Important Variables in States and Capitals

A$ Data for the state

B$ Data for capital

'NP$ Input for finding information

USED(X) Makes sure that states in quiz are not used

twice
RESPONSES Player's answer in quiz
^^$ Sees if player wants to continue

CH Player's choice from menu

CH2 Choice of information wanted

CH3 Choice of type of quiz wanted

Lf Loop for finding Information

DELAY Delay loop

L2 Loop to ask quiz questions

L3 Loop used to make sure that same state

has not been used twice in quiz
L4 Used to read remaining data

L5 Sets all USED(X)=:0

Important Lines in States and Capitals

5-7 Initialization

10-95 Sets up menu

100-140 Gets user's choice

150-230 Gets choice of information wanted

240-350 Finds capital of a state

400-500 Finds the state

800-998 Data

1003-1007 Sets all USED(X) to zero

1 01 0-1 090 Gets choice of quiz

1100 Beginning of quiz

1 1 20-1 1 40 Makes sure that random number has not been

used twice
1 1 60-1 1 80 Reads data to get to the data needed in the quiz
1300-1450 Asks questions, gets responses, sees if they

are correct
1500-1520 Sees if user wants to continue the quiz
1600 Computes the user's score

LEARNING THE EASY WAY

As you can tell from using these programs, computers can
make learning more enjoyable and less frightening for younger

people, who might be afraid of being scorned for their mistakes.
Computers can teach individuals at their own pace, and will
provide endless encouragement and congratulations for people
learning with the computer. See if you can make a program to
teach a subject in which you have an interest, and find out if
people using the program can learn as much or more than they
would with a teacher. You might be surprised at the results.

Chapter 4

Math and Your Computer

Since computers are basically ^^math machines" (they work only
with numbers and translate words into numbers before using
them), your ATARI 600XL or 800XL is very proficient at math. It
can handle addition, subtraction, multiplication, division,
trigonometric functions, exponents, and just about any
other mathematical formula you can give it.

Because of the ATARI'S prowess at mathematics, your
computer can be an excellent tool for solving your math prob-
lems, as well as testing you on your math abilities. In this chapter
we'll take a look at four programs that serve these purposes and
will prove how quickly and accurately the ATARI home comput-
ers can handle numbers.

CALCULATOR

This first program will serve the functions of an advanced
calculator. It will perform the four basic functions (add, subtract,
multiply, divide), trigonometric functions (like sine, cosine, tan-
gent), and find the square root of a number. This program takes
advantage of most of the ATARI'S math commands and can help
you by being a powerful "computer calculator," as shown in Fin
4-1. ^'

The first part of the program clears the screen and displays
the "menu" of options. The computer then allows you to choose
a function and input the number you wish to use with it.

SUPER CALCULATOR

FUNCTIONS

1,
2.
3,
4.
5.

ADD

SUBTRACT

MULTIPLY

DIVIDE

SQUARE

10.

SINE
COSINE
TANGENT
LOG
50

6. SQUARE ROOT

?10

PLEASE INPUT THE FUNCTION YOU WANT'? 3

AT THE PROMPT, PLEASE INPUT

THE APPROPRIATE NUMBERS? 5

Fig. 4-1. Computer Calculator.

10 GRAPHICS O

20 DEG

100 POSITION V,l

110 PRINT'-SUPER CALCULATOR"

120 PRINT

130 PRINT"FUNCTIONS: "

140 PRINT

1~0 PRINT"!. ADD 7. SINE"

160 PRINT"2. SUBTRACT 8. COSINE"

170 PRINT"3, MULTIPLY 9. TANGENT'

180 PRINT"4, DIVIDE 10. LOG"

190 PR I NT "5. SQUARE"

195 PRINT"6. SQUARE ROOT"

210 POSITION 5,15

220 PRINT NM; "

225 PRINT:PRINT

230 INPUT NM

240 PR I NT "PLEASE INPUT THE FUNCTION YOU WANT";

250 INPUT FUNC:PRINT"AT the PROMPT sign, PLEASE INPUT"

251 PRINT"THE APPROPRIATE NUMBERS"

The computer then goes to a predetermined line number
based on the value of your function. If the function number you
selected does not exist, the computer will go back to line 21 0 to
ask for your input once again.

300 ON FUNC GOTO 500,600,700,800,900,1000,1100,1200,
1300, 1400
310 GOTO 210

For some of these functions (like square root), only one
number (variable NM) will be necessary. Other functions require
a second number (variable NM2). In the lines below, you will see
that some of the functions INPUT to the variable NM2, while
others immediately work with the variable NM and return to the
functions menu. The result is displayed and the computer waits
for more input.

500 INPUT NM2

510 NM=NM+NM2

520 GOTO 210

600 INPUT NM2

610 NM=NM-NM2

620 GOTO 210

700 INPUT NM2

710 NM=NM*NM2

720 GOTO 210

300 INPUT NM2

310 NM-NM/NM2

820 GOTO 210

700 NM=NM*NM

'?10 GOTO 210

LOOO NM=SQR(NM)

1010 GOTO 210

1 1 00 NM=S I N ( NM )

1110 GOTO 210

12O0 NM=COS(NM)

1210 GOTO 210

1300 NM^'SINCNfD/COSCNM)

1310 GOTO 210

1400 NM=CLOG(NM)

1410 GOTO 210

1500 NM=INT(NM>

1510 GOTO 210

In all of the functions above, the computer returns to line 210
to display the result of the function and await input for another
problenn. You might want to add more functions to this program
using your own special equations. If you wish to do this, simply
add lines to the end of the program (your first added function
might be on lines 1 600 and 1610) and add the line number(s) to
the ON . . . GOTO statement in line 300.

Important Variables in Calculator

NM The number that is calculated

FUNG The function that is chosen

NM2 Second number for adding, subtracting,

or whatever

Important Lines in Calculator

20 Sets trigonometric functions to degrees

100-200 Sets up list of functions

220 Displays number

225-250 Gets number and function by which to calculate

300 Goes to chosen function

BASIC SKILLS CHECK-UP

!f you think that calculators and computers have "spoiled"
you into complete reliance on machines for simple mathematical
functions, you might want to try this program. Or you could let a
younger person use it to try out his or her skills at addition,
subtraction, and multiplication. The challenge of this program is

not only getting the problems correct, but also doing so in as little
time as possible.

The program begins by setting up the string arrays. It then
waits for you to hit a key and press < RETURN> so it can begin.

50 DIM A*(l>

60 DIM YN*(1)

100 GRAPHICS O

HO POSITION 7,8

120 PR I NT "BASIC SKILLS CHECK-UP"

130 POSITION 4,12

140 PRINT-HIT ANY KEY TO CONTINUE"

150 INPUT A*

The ATARI now clears the screen and shows you the three
options from which you may choose. Select one of these, and
press <RETURN>.

160 GRAPHICS O

170 POSITION 5,8

180 PRINT" 1. ADDITION"

185 POSITION 5,9

190 PRINT "2- SUBTRACTION"

195 POSITION 5,10

200 PRINT"3- MULTIPLICATION"

210 PRINT: INPUT CH

Because the computer has to set a certain limit how high the
^andom numbers can be used to test you, the ATARI takes into
consideration the function you have chosen. If you are going to
be doing addition or subtraction, the limit of the random numbers
will be from one to fifteen, since these are not too high for a
person adding or subtracting. On the other hand, since multipli-
cation is more difficult, the limit is set to nine. Also, the timer in the
ATARI (in bytes 19 and 20 in the computer's memory) is set to
zero. The computer then begins the FOR/NEXT loop to select
ten random numbers for your problems.

215 GRAPHICS 0

220 LIMIT=15

230 IF CH=3 THEN LIMIT=9

240 POKE 19,0: POKE 20,0

250 FOR TIMES=1 TO 10

270 NUMl = INT<LiriIT#RND<l)+l)

280 NUM2=INT (LIMIT*RND (1 ) +1 )

Based on your selection, the computer will present a
problem to you and accept an answer.

290 ON CH SOTO 300,320,340

300 PRINT NUM1;»+";NUM2; "=";

310 INPUT ANSWER: GOTO 500

320 PRINT NUt11;"-";NUM2; " = ";

330 INPUT ANSWER: GOTO 500

340 PRINT NUMl; "*";NUM2; "=";

350 INPUT ANSWER: GOTO 500

Once you have selected an answer the computer will check
to see if you are right or wrong; if you are correct, it will go to the
next question or repeat the question if you answered incorrectly.

This program is an excellent tool for sharpening up basic
math skills since you have to work against the clock to answer
the questions. To make it more difficult for the person using the
program (even if that happens to be you), try to limit the amount
of time in which questions can be answered. You could also
increase the high limit on the random numbers that can be
selected.

Important Variables in Basic Skills Check-Up

A$ Input to see if user is ready to continue

YN$ Input to see if user wants to use the program

again
CH User's choice of function

LIMIT Sets limit of random numbers to 15 when doing

addition or subtraction and to 9 when doing

multiplication

NUM1 First random number

NUM2 Second random number

A The time the user takes to complete the problems

ANSWER The user's answer

TIMES The loop which asks for the answers to ten

problems

SECONDS User's time (variable A) converted to seconds

Important Lines in Basic Skills Check-Up

50-210 Initialization to set up menu

220-230 Sets upper limit of random numbers

240 Sets time to zero

250-280 Gets two random numbers

290-350 Prints selected random operation on screen and

gets answer from user
500-560 Checks if answer is right or wrong

"^00 Tells user he is wrong, goes to ask question

once again
800 Tells user he's right

900-920 Gets time, converts it to seconds

930-940 Tells user his time
950-980 Asks if the user wants to try again

4+2=^6

CORRECT

6 + 9 = '? 14

WRONG

6 + 9 = '^ 15

CORRECT

3 + 8 = ';'

Fig. 4-2. Skills Check-Up.

ENTER THE LENGTH OF THE RADIUS.

?10

THE AREA IS 314.59

HIT ANY KEY TO CONTINUE.

Fig. 4-3. Geometry program finding the area of a circle.

GEOMETRY

This next program is basically a tool, since it will solve
geometry problems for you. With this tool you can find areas and
volumes; you can also discover how the computer finds the
answer to these problems. Figure 4-3 shows a sample problem.
To use Geometry, you simply select a particular function and
then give the computer the necessary data to solve the problem.

500 ON CH GOTO 510,530,550

510 IF ANSWER<>(NUM1+NUM2) THEN GOTO 700

520 GOTO 800

530 IF ANSWER<>(NU«1-NU«2) THEN GOTO 700

540 GOTO 800

550 IF ANSWER<>(NUM1*NUM2) THEN GOTO 700

560 GOTO 800

700 PRINT"WRaNG":GOTO 290

800 PRINT"CORRECT":NEXT TIMES

Once the ten math questions have been asked, the ATARI
will inform you of the time it took you to answer the problems, and

then ask if you would like to use the program again. If so, you can
select another function to practice. If not, the program will end.

900 A=PEEK<19)

9 1 0 SECDNDS=4 , 27* A

920 SECONDS=INT (SECONDS)

930 PRINT: PRINT

940 PRINT"YOUR TIME IS "; SECONDS;" SECONDS,"

950 PRINT: PRINT

960 PRINT"DO YOU WANT TO PLAY AGAIN";

970 INPUT YN*

980 IF YN*="Y" THEN RUN

First, the computer shows you the 16 different functions
available to you and lets you tell it which function you wish to use.

50 DIM ANYSd)

100 GRAPHICS O

110 PR I NT : PR I NT : PR I NT

120 PRINT" 1. AREA OF A RECTANGLE"

130 PR INT "2. AREA OF A SQUARE"

140 PRINT "3. AREA OF A PARALLELOGRAM"

150 PRINT"4. AREA OF A TRIANGLE"

160 PRINT"5. AREA OF A TRAPEZOID"

170 PRINT"6. AREA OF A CIRCLE"

180 PRINT" 7, AREA OF A SPHERE"

190 PRINT"B, AREA OF A CUBE"

200 PR I NT "9, AREA OF A CYLINDER"

210 PRINT" 10- AREA OF A SPHERE"

220 PRINT" 11. VOLUME OF A RECTANGULAR SOLID"

230 PRINT" 12. VOLUME OF A CUBE"

240 PRINT" 13- VOLUME OF A CYLINDER"

250 PRINT" 14. VOLUME OF A SPHERE"

260 PRINT" 15- VOLUME OF A CONE"

270 PRINT" 16, VOLUME OF A PYRAMID"

280 PRINT: PRINT: PRINT"PLEASe CHOOSE ONE."

290 INPUT CHOICE

Your ATARI will now go to the line number that performs the
function selected.

295 6RAPHICS O

300 ON CHOICE GOTO 350,400,500,600,700,800,900,1000,

1100,1200,1300,1400,1500,1600,1700,1800

Each Of the formulae below has to know certain facts to
calculate the answer to your problem. For instance, to find the
area of a square, the computer needs only the length of one side.
To find the volume of a cone, however, the computer needs to
find the radius of the base and the height of the cone. It finds out
this data by accessing certain subroutines found near the end of
the program. These subroutines will let you input the necessary
data. Because the computer can use them over and over again,
this program is shorter and more efficient than it would be if, for
each of the problems, the computer had INPUT statements
exclusively for that type of function. In the lines below, the
computer will access the subroutines needed to get the neces-
sary data, and then perform the function, go to the appropriate
line number, and displays the result.

350 GOSUB 2000

360 GOSUB 2100

370 AREA-LN*WD

380 GOTO 6000

400 GOSUB 2000

410 AREA=LN*LN

420 GOTO 6000

5O0 GOSUB 2200

510 GOSUB 2300

520 AREA=BA*HT

530 GOTO 6000

600 GOSUB 2200

610 GOSUB 2300

620 AftEA=<BA*HT)/2

630 GOTO 6000

700 GOSUB 2200

710 GOSUB 2400

720 GOSUB 2300

730 AREA=< (BA+BA2)/2)*HT

740 GOTO 6000

800 GOSUB 2500

810 AREA=(RD*RD>*3_ 14159

B20 GOTO 60OO

900 GOSUB 2000

910 GOSUB 2100

920 GOSUB 2300

930 AREA=<2*LN*WD)+(4*LN*HT)

940 GOTO 6000

1000 GOSUB 2000

1010 AREA=6*LN*LN

1020 GOTO 6000
LI 00 GOSUB 2500

:ill0 GOSUB 2300

:. 120 AREA=2*RD*HT*3- 14159

1 130 GOTO 6000

J 200 GOSUB 2500

3 210 AREA=4*RD*RD*3. 14159

] 220 GOTO 6000

1300 GOSUB 2000

1310 GOSUB 2100

1320 GOSUB 2300

1330 VOL=LN*WD*HT

1.340 GOTO 6500

1400 GOSUB 2000

1410 VOL=LN*LN*LN

1420 GOTO 650O

1500 GOSUB 2300

1510 GOSUB 2500

1520 V0L=3. 14159*RD*RD*HT

1530 GOTO 6500

1600 GOSUB 2500

1610 V0L=(4*3. 14159*RD*RD*RD)/3

1620 GOTO 6500

1700 GOSUB 2300

1710 GOSUB 2500

1720 V0L=(3. 14159*RD*RD*HT)/3

1730 GOTO 65O0

1800 GOSUB 2200

1810 GOSUB 2300

1820 V0L=(BA*BA*HT)/3

1830 GOTO 6500

The lines below are the subroutines mentioned earlier.
They allow you to enter the width, height, radius, or whatever
else is needed to calculate an accurate answer about a geomet-
ric shape or object.

2000 PRINT: PR I NT "ENTER THE LENGTH."

2010 INPUT LN

2020 RETURN

2100 PRINT: PRINT"ENTER THE WIDTH."

2110 INPUT WD

2120 RETURN

2200 PRINT; PR I NT "ENTER THE LENGTH OF THE BASE,"

2210 INPUT BA

2220 RETURN

2300 PR I NT: PR I NT "ENTER THE HEIGHT."

2310 INPUT HT

2320 RETURN

2400 PRINT: PR I NT "ENTER THE LENGTH OF THE SECOND BASE."

2410 INPUT BA2

2420 RETURN

2500 PRINT: PR I NT "ENTER THE LENGTH OF THE RADIUS,"

2510 INPUT RD

2520 RETURN

Once the ATARI has found the answer to your problem, it
will display the area or the volume, whichever is appropriate.

6000 PRINTrPRINT

6010 PR I NT "THE AREA IS *' ; AREA

6020 GOTO 7000

6500 PRINTrPRINT

6510 PR I NT "THE VOLUME IS " ; VOL

The ATARI will then wait for you to press a key followed by
the <RETURN> key to try another problem.

7000 PRINTrPRINT

7010 PRINT "HIT ANY KEY TO CONTINUE."

7020 INPUT ANYS

7030 GOTO 100

Again, you can put other formulae into this program, but you
will have to compensate for the additions in the other parts of
your program (such as the ON . . . GOTO statement). Inciden-
tally, not only is this an excellent tool for calculating the answers
to problems, but it could also be used (by a high school teacher,
for example) to check geometry tests.

Important Variables in Geometry

CHOICE Input for the figure chosen by the user

AREA Area of a figure

VOL Volume of a figure

LN Length

WD Width

HT Height

BA Base length

BA2 Second base length

RD Radius

ANY$ Used to see if user wants to continue

Important Line Numbers in Geometry

50-290 Sets up menu

300 Goes to selected figure

350-1 830 Calculates areas or volume

2000-2520 Gets necessary input from user

6000-6020 Tells user the area

6500-6510 Tells user the volume

7000-7030 Waits until user is ready to continue

LENGTH CONVERTER

This last program is also a tool. It can convert linear units of
one type, specifically measurements of length in either metric or
"standard" units— as nonstandard as the American system is
with respect to the rest of the world— into linear units of another
type. For example, you could change a number of kilometers into
miles, a number of centimeters into inches, or a number of
kilometers into meters. You can change from any unit to any
other unit, even metric to metric or standard to standard. A
sample screen can be found in Fig. 4-4.

As usual, the first part of this program shows a menu of the
different selections. You can chose from this menu the number
of the unit you will give the computer and the unit to which you
want to change. After the computer shows you the menu, it goes
to the subroutine at line 4000, which will let you select both units
and the quantity involved.

50 DIM INP*(1)
100 GRAPHICS O
200 POSITION 10,3

LENGTH CONVERTER

1. INCHES

2. FEET

3. YARDS

4. MILES

5. CENTIMETERS

6. METERS

7. KILOMETERS

WHICH IS THE UNIT THAT YOU WANT
TO CHANGE FROM?

Fig. 4-4. Length Converter.

250 PRINT"LEN6TH CONVERTER"

260 PRINT: PRINT

300 PRINT" 1. INCHES"

310 PRINT"2. FEET"

320 PR I NT " 3 , YARDS "

330 PRINT"4. MILES"

340 PRINT"5. CENTIMETERS"

350 PRINT"6, METERS"

360 PR I NT " 7 . K I LOMETERS "

370 GOSUB 4000

The ATARI will then go to a line number based on the value
of the variable UNIT1. At that line number will be another ON . . .
GOTO statement which will, based on the value of UNIT2, find
the line which will convert your number from the first unit to the
second unit amount. At that point, the ATARI will go to line 5000
to give you the answer to the question.

380 ON UNITl GOTO 400,500,600,700,800,900,1000

400 ON UNIT2 GOTO 410,420,430,440,450,460,470

410 AM0UNT2=AM0UNT1:G0T0 5000

420 AMOUNT2=AMOUNT1/12:GOTO 5000

430 AM0UNT2=AM0UNT 1/36: GOTO 5000

440 AM0UNT2=(AM0UNTl/12)/5280:GOTO 5000

450 Ah0UNT2=AM0UNTl*2.54:G0T0 5000

460 Ari0UNT2=AM0L)NT 1 * . 0254 : GOTO 5000

470 AM0UNT2=( ( AMOUNT 1 / 12) /5280) #. 62: GOTO 5000

500 ON UNIT2 GOTO 510,520,530,540,550,560,570

510 AM0UNT2=AM0UNT 1*12: GOTO 5000

520 AMOUNT2=AMOUNTl:GOTO 5000

530 AM0UNT2=AMOUNTl/3:GOT0 5000

540 AMOUNT2=AMOUNTl/5280:6aTO 5000

550 AMOUNT2=(AMOUNTl*12)*2. 54s GOTO 5O00

560 AM0UNT2=Af10UNT 1*0. 3048: GOTO 5000

570 AM0UNT2=(AM0UNT1/5280)*1.61:G0T0 5000

600 ON UNIT2 GOTO 610,620,630,640,650,660,670

610 AM0UNT2=AM0UNT1*24:G0T0 5000

620 AM0UNT2=AM0UNT1*3:G0T0 5000

630 AM0UNT2=AM0UNT1:G0T0 5000

640 AM0UNT2= ( AMOUNT 1 *3 ) /5280: GOTO 5000

650 AMOUNT2=(AM0UNTl*24)*2.54:GOT0 5000

660 AMOUNT2=AM0UNTl*0.91:G0T0 5000

670 AM0UNT2= (AMOUNTl/ 1760) « 1.61: GOTO 5000

700 ON UNIT2 GOTO 710,720,730,740,750,760,770

710 AMOUNT2=(AM0UNTl*528O)*12:G0T0 5000

720 AMOUNT2=AMOUNT 1*5280: GOTO 5000

730 AM0UNT2=AM0UNT 1 * 1 760: GOTO 5000

740 AM0UNT2=AM0UNT1:G0T0 5000

750 AMaUNT2= (AMOUNT! *&3360) #2, 54: GOTO 5000

760 AMOUNT2=< AMOUNT 1*1. 61)* 1000: GOTO 5000

770 AM0UNT2=AM0UNT1*1-61:G0T0 5000

800 ON UNIT2 GOTO 810,820,830,840,850,860,870

810 AM0UNT2=AM0UNT1*0.39:G0T0 5000

820 AMOUNT2= ( AMOUNT 1 *0 . 39 ) / 1 2 : GOTO 5000

830 AM0UNT2=( (AM0UNT1*0. 39) /12) /3: GOTO 5000

840 AMOUNT2=< (AMOUNT 1*0. 39/1 2) >*5280: GOTO 5000

850 AMOUNT2=AMOUNTl:GOTO 5000

860 AM0UNT2=AM0UNT 1/100: GOTO 5000

870 AM0UNT2=AM0UNT1/ 1000: GOTO 5000

900 ON UNIT2 GOTO 910,920,930,940,950,960,970

910 AM0UNT2=AM0UNTl/0, 254: GOTO 5000

920 AMOUNT2=(AMOUNT1/0- 0254) /12r GOTO 5000

930 AMOUNT2=AMOUNTl*l-O9:G0T0 5OO0

940 AM0UNT2=( (AM0UNTl/.025 4)/12)*5280)*12:G0T0 5000

950 AM0UNT2=AM0UNT1* 100: GOTO 5000

960 AMOUNT2=AMOUNT 1 : GOTO 5000

970 AM0UNT2=AM0UNT1/ 1000: GOTO 5O0O

1000 ON UNIT2 GOTO 1010,1020,1030,1040,1050,1060,1070

1010 AM0UNT2=( (AMOUNT 1*. 62) *5280)* 12: GOTO 5000

1020 AM0UNT2=(AM0UNT1*0.62)*5280:G0T0 5000

1030 AM0UNT2=(AMaUNTl*0. 62)* 1760: GOTO 5000

1040 AMOUNT2=AMOUNTl*0-62:GOTO 5000

1050 AMOUNT2=AMOUNT1*100000:GOTO 5000

1060 AM0UNT2=AM0UNT1* 1000: GOTO 5000

1070 AMOUNT2=AMOUNTl:GOTO 5000

The subroutine below will let you Input the unit from which
you want to change, the amount of the unit, and the unit to which
you want to change.

4000 PRINT: PRINT"WHICH IS THE UNIT THAT YOU WANT TO
CHANGE FROM?"
4010 INPUT UNITl

4020 PRINT: PR I NT "WHAT IS THE AMOUNT OF THIS UNIT?"

4030 INPUT AMOUNT 1

4040 PRINT: PR I NT "WHAT UNIT DO YOU WISH TO CHANGE TO?"

4050 INPUT UNIT2

4060 RETURN

Finally, the ATARI will tell you the answer in the new unit,
and then wait for you to press a key plus <RETURN> to do
another conversion.

5000 PRINT! PR I NT "THE AMOUNT OF THE NEW UNIT IS " ; AM0UNT2
5010 PRINT:PRINT"HIT ANY KEY TO CONTINUE."
5020 INPUT INP*
5030 GOTO 100

This completes this program, which will serve as a helpful
conversion tool. You may also want to utilize this program as a
testing machine, having a person figure out conversion prob-
lems and then testing his or her answers against the computer's.

Important Variables in Length Converter

INP$ Input to see if user wants to continue

'JNITI The unit of measure that the user wants to

convert
AM0UNT1 The amount of this unit

UNIT2 The unit that to which the user wants to

change
AMOUNT2 The amount of the above

Important Lines in Length Converter

50-370 Initialization/Prints Menu

380 Goes to selected unit

400-1070 Converts to selected unit

4000-4060 Gets necessary input

5000 Gives user the answer

5010-5030 Waits until the user wants to continue

This completes our exploration of how the computer can
work with math. After using these programs, you will discover
that your ATARI is an excellent tool for mathematics. You may
write some programs yourself covering other areas of math,
such as calculus, graphing, and geometry— accompanied by
graphics to show the various geometric shapes and their for-
mulae.

Chapter 5

Graphics Programs for the ATARI

The ATARI home computers can produce high-quality color
graphics with only a few simple commands. It is certainly worth
our while to take a look into the power of the graphics of the
ATARI and explore some of its uses.

TERMS YOU NEED TO KNOW

Before we begin examining the BASIC programs in this
chapter that work with the graphics of the ATARI, there are a few
terms you need to know so you'll understand what I am talking
about when I mention such things as hue, luminance, and high
resolution.

Color. There are a total of 256 different colors you can utilize
on the ATARI home computers, although some graphics modes
don't support this many colors. In fact, in the very intricate and
detailed graphics modes, as few as two colors may be available.

Graphics. These are the pictures (as opposed to the words
and numbers) you see on the screen as in Fig. 5-1 . Bar graphs,
line graphs, spaceships in arcade games, and any othertypes of
visual images you see can be called graphics.

Low Resolution. Graphics which are rough, not well-defined,
and not accurately representative of what they are supposed to
be (for instance, graphics showing a ship which doesn't exactly
look like a ship) are low-resolution graphics. These don't take up
very much memory and are quite simple to program, but they are

WHAT IS THE FORMULA FOR THIS SHAPE?

ENTER ANSWER'^

Fig. 5-1. A screen showing graphics.

HERE ISA TRIANGLE

Fig. 5-2. Low-resolution graphics.
70

low in quality and aren't appropriate for things such as arcade
games or line graphics, which generally require high resolution.
For things such as bar graphs or simple charts, however, low
resolution usually will suffice. Figure 5-2 is an example of low
resolution.

High Resolution. This is the opposite of low resolution, since
these graphics are sharp, very well-defined, and take up a
significant amount of memory, time, and effort to complete and
draw. Figure 5-3 shows high-resolution graphics.

Hue. This is a variation of a color. Its gradation along the
spectrum of visible light from red to violet. With a change in hue,
a color's appearance will also change.

Luminance. This is the "brightness" of a color. If you in-
crease the luminance, the brightness increases.

Now that we have learned the definitions of these terms, we
can take a look at the four different programs in this chapter.

COLORBAR

Using this first program is an excellent way to learn the
significance of hue and luminance in affecting the way a color
appears on the screen. To use this program, simply press the H

HERE ISA TRIANGLE

Fig. 5-3. High-resolution graphics.

key to increase the value of the hue, SHIFT-H to decrease the
value of the hue, L to increase the luminance, and SHIFT-L to
decrease the luminance.

The first part of the program puts the ATARI into graphics
mode, makes certain that the values of hue and luminance are
zero, and shows the values of both hue and luminance:

50 GRAPHICS 1

60 HUE=0

70 LUM=0

100 POSITION 1,1

110 PRINT "HUE IS ";HUE

115 PRINT "LUMINANCE IS ";LUM

At this point, color register four is set to the values of HUE
and LUM; the ATARI begins monitoring the keyboard in case
you press anything. If you press H, SHIFT-H, L, or SHIFT-L, the
computer will go to the appropriate line number. If not, it will go
back to line 130 to go through the process again.

120 SETCOLOR 4, HUE, LUM

130 A=PEEK(764)

140 IF A=57 THEN 2O0

150 IF A=0 THEN 300

160 IF A=121 THEN 400

170 IF A=64 THEN 500

180 GOTO 30

The different routines for changing hue and luminance are
all basically the same. When the computer has finished making
the changes in the variable specified, it goes to line 600 to "clear
ouf the value in variable A. This keeps it from "thinking" that the
key you just pressed is being pressed again.

200 IF HUE=15 THEN 600
210 HUE=HUE+1
220 GOTO 600

300 IF LUM=14 THEN 600

310 LUri=LUM+2

320 GOTO 600

400 IF HUE=0 THEN 600

410 HUE=HUE-1

420 GOTO 600

500 IF LUM=0 THEN 600

510 LUM=LUf1-2

520 GOTO 600

600 A=255

610 POKE 764,255

615 PRINT

620 GOTO 100

As you can see at line 620, the program keeps looping back
to a point near the beginning so you can change the hue and
luminance repeatedly. This program is helpful for finding the
particular shades of color you need for your programs and also
for learning about the significance of hue and luminance. You
also might want to try changing the first value in the SETCOLOR
statement (the register number, which is shown here as 4) to a
different number to see the results.

Important Variables in Cotorbar

HUE Hue Value of SETCOLOR command

LUM Luminance value

A Value of key pressed

Important Line Numbers in Colorbar

110-115 Tells user the color values

120 Sets the color

1 30-1 80 Gets keyboard value

200-220 Adds 1 to hue value

300-320 Adds 2 to luminance value

400-420 Subtracts 1 from hue value

500-520 Subtracts 2 from luminance value

600-620 Resets keyboard value

SHAPES

Here is a simple program to teach you how to draw certain
shapes, like three-dimensional cubes and two-dimensional
triangles, on the video screen. The program will display a menu
of four different shapes, plus an option to end the program. If you
select a shape, it will be shown with the vertices used to draw it. If
you want to end the program, simply select Option 5 and the
program will stop. Figure 5-4 shows a sample rectangle.

At the beginning of the program, room is made for the C$
variable, the screen is cleared, and the menu, is displayed:

5 DIM C*<1)

10 GRAPHICS O

20 POSITION 7,7

30 PRINT "SAMPLE SHAPES LIBRARY"

40 POSITION 9, 10

50 PRINT "1. RECTANGLE"

60 POSITION 9,11

70 PRINT "2. TRIANGLE"

VERTICES AT 40, 40 AND 80, 40 AND
80, 80 AND 40, 80

Fig. 5-4. Sample screen from Shapes.
74

80 POSITION 9, 12

90 PRINT "3. BOX"

100 POSITION 9,13

110 PRINT "4, ABSTRACT"

120 POSITION 9,14

130 PRINT "5. END"

The program allows you to input your choice; it then acts on
the value of your choice by going into high-resolution graphics
mode, establishing a color for graphics, and going to the appro-
priate line number.

140 INPUT CHOICE

145 GRAPHICS 14

147 COLOR 3

150 ON CHOICE GOTO 200,300,400,500,600

The shapes below are rectangle, triangle, box, and
abstract, respectively. As you can see, the PLOT and DRAWTO
statements are used to construct the shapes, while the PRINT
statement displays the vertices used to draw the shape.

200 PLOT 40,40

210 DRAWTO QO, 40: DRAWTO 80,80

220 DRAWTO 40,80: DRAWTO 40,40

230 PRINT "VERTICES AT 40,40 AND 80,40"

240 PRINT "AND 80,80 AND 40,80-"

250 GOTO 700

300 PLOT 80, 20

310 DRAWTO 100,80: DRAWTO 60,80

320 DRAWTO 80,20

330 PRINT "VERTICES AT 80,20 AND 100,80"

340 PRINT "AND 60,80."

350 GOTO 700

400 PLOT 40,40

410 DRAWTO 80,40: DRAWTO 80,80

420 DRAWTO 40,80: DRAWTO 40,40

430 DRAWTO 60,20: DRAWTO 100,20

440 DRAWTO lOO, 60: DRAWTO 80, SO

445 PLOT 80,40

450 DRAWTO 100,20: PLOT 40,80

460 DRAWTO 60,60: DRAWTO 100, 60

470 PLOT 60,60: DRAWTO 60,20

480 PRINT "VERTICES AT 40,40 AND 80, 40 AND 80,80"

490 PRINT "AND 40,80 AND 60,20 AND 100,20 AND "

492 PRINT "100,60 AND 60,60"

495 GOTO 700

5O0 PLOT 20,20

510 FOR L00P1=1 TO 30

520 X=INT ( 160*RND ( 1 ) +1 )

530 Y=INT ( 160*RND (1 ) +1 )

540 DRAWTO X,Y

550 NEXT LOOPl

560 PRINT "30 RANDOM VERTICES"

570 GOTO 700

Option 5, '^End Program," simply clears the screen and
ends the program.

600 GRAPHICS O
610 END

On the other hand, if you have selected a shape, you can
draw another one by pressing C and then <RETURN> in an-
swer to the question below:

700 PR I NT "INPUT C TO CONTINUE.";
710 INPUT C^
720 GOTO 10

When you are drawing different shapes, you certainly don't
have to use the vertices shown here, but you should examine the
relationships of the vertices so you can draw similar shapes in
your own programs.

Important Variables in Shapes

CHOICE Input user's choice of a shape

LOOP1 Loop used to make a random, abstract shape

X,Y Coordinates for abstract pattern

C$ Input used to play again or not

Important Line Numbers in Shapes

5-150 Initialization to get input from user and

go to chosen shape
200-250 Draws rectangle

300-350 Draws triangle

400-495 Draws a box

500-570 Draws an abstract figure

600-610 Ends program

700-720 Asks for input to continue or not

DRAWER

For sketching graphics on the screen, as in Fig. 5-5, you can
use this short program that allows you to use the following keys
for the following functions:

KEY FUNCTION

V Move Drawer up

B Move Drawer down

G Move Drawer left

H Move Drawer right

Q Turn color to cyan

W Turn color to orange

E Turn color to blue

R Go to "non-drawing" mode

The program begins by going into full-screen high-
resolution graphics mode and assigning COLOR 2 to the
graphics, while the X and Y values are set to zero:

Fig. 5-5. A drawing program example.

10 GRAPHICS 7+16
20 COLOR 2
30 X=0:Y=0

Then, the point in the upper left-hand corner of the screen is
drawn, and the keyboard byte (764) is "cleared" by poking a
value of 255 into it:

40 PLOT 0,0
100 POKE 764,255

At this point, the computer begins monitoring byte 764. Any
activity in that byte will be interpreted by the computer and acted
upon by the ATARI:

no K=PEEK(764) : IF K=255 THEN SOTO 110
120 IF K=47 THEN C0L=2: GOTO 400

130 IF K=46 THEN C0L==1:G0T0 400

140 IF K=42 THEN COL=3:GOTO 400

145 IF K=40 THEN COL=0:GOTO 400

150 IF K=43 THEN Y^Y-l:GOTO 200

160 IF K=61 THEN X=X-1:G0T0 200

170 IF K=57 THEN X=X+1:G0T0 200

180 IF K-:=21 THEN Y==Y+l:GOTO 200

190 GOTO 100

If the user happens to draw beyond the boundaries of the
screen, the ATARI automatically corrects the mistake:

200 IF Y<0 THEN Y=0

210 IF Y>95 THEN Y=95

220 IF X<0 THEN X=0

230 IF X>159 THEN X=159

In addition, if the current.color of the cursor is 0 (blank), then
a special routine at line 500 is accessed to blink the drawer
temporarily. Otherwise the graphics are drawn on the screen
and the computer goes back to the "keyboard detect" sequence.

235 IF COL=0 THEN GOSUB 500

240 DRAWTO X , Y

250 GOTO 100

400 PLOT X,Y

420 COLOR COL

430 GOTO 100

:500 COLOR 2

;510 PLOT X,Y

1520 FOR DELAY-1 TO 50: NEXT DELAY

530 COLOR O

:540 PLOT X,Y

1550 RETURN

When you want to nnove around the screen without drawing,
go into the "non-draw" mode. Othenwise, select a color of your
choice and draw with that. This program can be helpful when you
are developing graphics or just experimenting with the potential
of the ATARI home computer.

Important Variables in Drawer

X,Y Plot values

K Keyboard value

COL Color register value

DELAY Used for delay loop

Important Lines in Drawer

10-40 Initialization

1 00-1 90 Gets keyboard input

200-230 Sees if drawer is going off the edge

235 If drawing in erase mode, computer makes

a point blink to show where the drawer is.
240 Does actual drawing

400-430 Changes drawer to desired color

500-550 When in erase mode, makes a point

blink to show position

GRAPH

This program has a practical purpose in that you can use it
for inputting data and having that data displayed in line graph
form similar to Fig. 5-6. To use this program, simply type in the
number of data items you will be entering (up to 1 0), then enter
each value, which may range from 0 to 159. Once you have
entered all of your numbers, the computer will plot it on the
graph; you then have the option to draw another one.

First of all, the program sets aside room for its variables,
clears the screen, and asks how many items there are to be
entered:

5 DIM ITEM (10)

7 DIM Y*( 1)

lO GRAPHICS O

20 PRINT "HOW MANY ITEMS? (UP TO 10)"

30 INPUT ITEMS

Fig. 5-6. A line graph.

Then a loop begins so you can enter each of the items:

40 FOR L00P1=1 TO ITEMS

50 PRINT "ENTER AMOUNT OF ITEM ";LOOPX

60 PRINT " (UP TO 159) "

70 INPUT I

80 ITEM(L00P1)=I

90 NEXT LOOPl

Once you have put in all of your items, the ATARI computes
how much space on the X-axis should be allocated for each item
of data. It then goes into high-resolution graphics mode and
draws the two axes:

1 00 ADDX=^ I NT ( 1 59/ 1 TEMS >

] 10 GRAPHICS 14

120 COLOR 1

125 PLOT 0,0

130 DRAWTO 0,159
140 DRAWTO 159,159

For graphing, the computer simply plots the first point and
then goes to each successive data item you gave it using the
DRAWTO statement. When it has finished you have your line
graph. The computer asks you if you would like another graph,
the answer to which question causes it to respond accordingly.

150 x=o

160 PLOT X,159-ITEM(1)

170 FOR L00P2=2 TO ITEMS

180 DRAWTO X+ADDX,159-ITEM(LOOP2)

190 X=X+ADDX

200 NEXT LaOP2

210 PRINT "WANT ANOTHER SRAPH"i INPUT Y*

220 IF Y*="Y" THEN RUN

230 GRAPHICS O

You might also try modifying this program to support bar
graphs or line graphs that are "filled in" below the graph lines, so
that a solid exists where there was space before.

Important Variables in Graph

ITEM (X) Data for items on X-axis
ITEMS Input for number of items on X-axis

L00P1 Used to ask for input amount for above

I Input for entering data

ADDX Used when dividing up the X-axis so there

will be enough room for all pieces of data
L00P2 Used to graph each amount on the ghd

X Number of positions on X-axis available

V$ Sees if you want to draw another graph or not

Important Line Numbers in Graph

20-90 Gets information for the graph

100 Gets amount to add to the value for the X-axis

each time a new point in drawn

120-140 Draws both axes

150-160 Graphs first item

1 70-200 Graphs other items

210-230 Checks to see if you want to draw another graph

These programs have only begun to touch upon the
ATARI'S graphics capabilities, but they do give you an idea of the
uses for this particular aspect of the computer. You might also
want to try expehmenting with the ATARI graphics commands,
working out program ideas that you could use for learning
geometry, helping in business, or creating educational software
for younger people. Whatever your purpose, the ATARI graphics
capabilities should serve you well— as long as you use the
available memory efficiently.

Chapter 6

Games

The ATARI home computers are probably best known for their
ability to support high-quality games. These games, most of
them "arcade-type/" have provided hours of entertainment for
home computer owners— especially considering how much
better computer games are over home video game systems.

In this chapter, we will be taking a look at three game
programs. Because the BASIC language isn't as fast and effi-
cient as the machine language in which most arcade games are
written, these games are not "arcade-type." Nevertheless, they
are still entertaining games which will teach you more about how
BASIC may be used.

GUESS MY NUMBER

The first game, a very basic one at that, is called "Guess My
Number/' and it involves trying to guess a random number the
computer has generated and stored in its memory. The number
can range from 1 to 100. Once you have guessed the number,
the computer will tell you how many guesses it took your deduc-
tive reasoning to find the number.

The program itself is extremely simple, since it uses primar-
ily the RND and the INPUT statements. The first line creates a
string, YN$, that can hold one character:

1 DIM YN^d)

Then the screen is cleared and the variable which records
how many tries have been made is set to 1 :

2 GRAPHICS 0
5 TIMES=1

The random number is then generated by the RND state-
ment, and the computer asks the user to guess the number.

1 0 NUMBER= I NT ( 1 00*RND ( 1 > + 1 )
20 PR I NT "WHAT IS MY NUMBER?
30 INPUT GUESS

Once the guess has been input, the computer checks
whether it is correct, too low, or too high. If the guess is greater
than 100, It returns to the question at line 20. Otherwise, the
computer will check the condition of the number and go to the
appropriate line number:

40 IF GUESS > 100 THEN 20

50 IF GUESS >NUMBER THEN 80

60 IF GUESS< NUMBER THAN 110

70 IF GUESB=NUMBER THEN 140

Once it reaches the line number, the computer takes ap-
propriate action for whatever the guess might be. If the guess Is
too high, the computer goes to this routine:

80 PRINT "MY NUMBER IS LOWER"
90 TIMES=TIMES+1
100 GOTO 20

If the guess is too low:

110 PRINT "MY NUMBER IS HIGHER"
120 TIMES=TIMES+1
130 GOTO 20

Finally, If the guess is correct, the computer tells you how
86

many guesses it took you to find the correct number. It then asks
whether you would like to play again or not, taking appropriate
action on your response:

140 PRINTsPRINT

150 PRINT"YOU GOT MY NUMBER RIGHT IN "; TIMES; " GUESSES. "

160 PRINT"DO YOU WANT TO PLAY AGAIN?"

170 INPUT YN*

180 IF YN*="Y" THEN 2

This completes the program. When you are playing it, try to
see how few guesses it takes you to guess the computer's
number. A sample screen is. shown in Fig. 6-1.

YN$
TIMES

Important Variables in Guess My Number

Input to see if player wants to play again or not
Used to count number of guesses the player
needed to guess the correct number

WHAT IS MY NUMBER'?

?50

MY NUMBER IS LOWER

WHAT IS MY NUMBER'?

Fig. 6-1. Guess My Number.

NUMBER A random number between 1 and 100
GUESS The player's Guess

Important Line Numbers in Guess My Number

10 Gets random number

20-30 Gets player's guess

40-70 Checks to see what player guesses

80-130 Tells player whether number is higher

or lower than his guess

SIMON SAYS

This program is a memory game, since you must remember
a sequence of colors and sounds the computer gives you. You
select the difficulty level (how long the colors and sounds are
shown and played) along, with the number of colors and sounds
you must remember. The computer shows and plays the colors
and sounds, and then you tell it what you remember. Afterwards
you may play again, perhaps to try a more difficult level, or stop
the game.

To set up the game, 1 programmed the computer to set up
the variables RAN and RESPONSES and clear the screen:

10 DIM RAN(25)

20 DIM RESPONSE* (1)

50 GRAPHICS O

The computer then asks how many screens were wanted.
The more screens there were, the harder it will be to remember
all of them.

hO POSITION 4,9

70 PR I NT "HOW MANY SCREENS DO YOU WISH TO TRY?"

72 POSITION 4, 13

75 INPUT TIMES

The computer is then programmed to ask what difficulty
level is desired. The difficulty level determines what period of
time the color and sound will be shown and played. The higher

the number the longer the period, and thus the easier it is to
remember the sequence.

80 POSITION 4, 15

85 PR I NT "ENTER DIFFICULTY LEVEL (1-3)"

90 POSITION 4,16

lOO PR I NT "LEVEL 1 IS THE MOST DIFFICULT"

110 INPUT LEVEL

1 20 DELAY=LEVEL* 1 00

The computer then clears the screen and begins the loop to
select the random colors:

130 GRAPHICS O

140 FDR L00P1=1 TO TIMES

Once the loop is running, random numbers (between 1 and
4) are selected, the screen is cleared, and the computer access-
es the appropriate combination of color and sound in accor-
dance with the randomly chosen number.

200 RAN ( LOOP 1 ) = I NT ( RND ( 1 ) *4 ) + 1

210 GRAPHICS O

220 ON RAN ( LOOP 1) GOTO 300,400,500,600

The routines for the four different colors and sounds are as
follows:

300 SETCOLDR 2,2,8

310 SOUND 0,100,14,15

320 GOTO 700

400 SETCOLOR 2,12,8

410 SOUND 0,50,8,15

420 GOTO 700

500 SETCOLOR 2,8,8

510 SOUND 0,50,14,15

520 GOTO 700

600 SETCOLOR 2,4,5

610 SOUND 0,250,14,15

The routine at line 700 delays for a short while so the color
and sound will remain on. Then the computer clears the sound
currently being played and checks to see if it should play another
sound and show another color. If so, it continues the L00P1 . If
not, it goes to line 800.

700 FOR L00P2=^l TO DELAY; NEXT L00P2

710 SOUND 0,0,0,0

720 IF LG0P1=TIMES THEN 800

730 NEXT LOOPl

At line 800, the computer begins the loop, which asks you
which color was on the screen. It will continue asking you this
until you have responded with the correct answer to all of the
colors. Once it has finished this loop, it will move on to the rest of
the program.

800 FDR L00P3=1 TO TIMES

810 GRAPHICS O

820 POSITION 6,6

830 PRINT" 1. ORANGE"

835 POSITION 6,7

840 PRINT"2. GREEN"

845 POSITION 6,8

850 PRINT"3. VIOLET"

855 POSITION 6,9

860 PRINT"4- RED"

870 POSITION 4,11

880 PR I NT "WHICH WAS COLOR SCREEN NUMBER " ; L00P3

890 INPUT ANSWER

900 IF ANSWER<>RAN(L00P3) THEN 1000
910 NEXT LQOP3

The remainder of the program either congratulates the
player for answering all of the questions correctly or tells the
player he input a wrong answer. After a win or lose has been
called, the computer asks if the player would like to play the
game again, so that it may take appropriate action.

?15 PRINT: PRINT"GOOD JOB ! "

920 PRINT: PRINT

930 PRINT"DO YOU WANT TO PLAY AGAIN?"

940 INPUT RESPONSE*

950 IF RESPONSE*="Y" THEN RUN

960 END

970 POSITION 6, 14

::010 PR INT "WRONG, , .YOU MISSED THAT COLOR,"

;.020 GOTO 920

This game Is good for working for memory and you should
1 ry to see just how many colors and sounds you can retain in your
mind. You also might want to try increasing the difficulty level for
added challenge in the game.

Important Variables in Simon Says

RAN(X) Random number (1 through 4) corresponding

to a color

RESPONSES Your response to whether you want to play

again or not
l"IMES Input for number of screens to try

LEVEL Input for level of difficulty

L00P1 Loop to display the random colors

DELAY Used to delay loop in accordance with the

choice picked when "Enter difficulty level

(1-3)" is asked
L00P2 Delay loop

LOOPS Asks for a certain number of answers,

equivalent to the value of the variable TIMES

ANSWER Input for the color the player thinks is correct

Important Line Numbers in Simon Says

70-100 Gets input from player

120 Sets length of delay used when showing each

color
140-730 Displays a certain number of colors

equivalent to the variables TIMES
200 Gets a random color (SETCOLOR value

ranging from 1 to 4)
220 Goes to randomly selected line number

700 Delay to display color on the screen for a

certain length of time
710 Turns off sound

800-910 Asks play what each color was
915 Tells player he got everything right

920-960 Asks "Do you want to play again?'"
1010 Tells player that he did not guess a color

correctly

BLACKJACK

Blackjack or "21 " is a popular card game in which you try to
beat the "dealer" (the ATARI) by getting a score as close to the
number of 21 as possible, without going over. You can also get a
jack and an ace, which is an automatic win called "blackjack"
(Fig. 6-2). Of course, the dealer could get blackjack or get closer
to 21 than you after you decide not to "take another hit" (get
another card). Simply try to get as close to 21 as you can, but
avoid a "bust," which occurs when you go over 21. Keep in mind
that the values for the cards are the same as their face value ; the
jack, king, and queen have a value of 1 0, while the ace can have
values of 11 or 1.

"Blackjack" begins by setting up the variables for the pro-
gram and clearing the screen:

10 DIM RAN<52):DIM DEALT (52)

15 DIM CARD(52):DIM A*(2)

20 GRAPHICS O

30 M0NEY=100

The computer then "shuffles" the cards by assigning each
card a unique value. This routine takes a while, since it must read
data from lines 2000 through 2030 (also shown below) and make
certain that the card it selects for variable is unique— so you
won't wind up with a deck of 15 queens.

40 PR I NT "SHUFFLING"

45 NM=0

50 FOR L00P3=1 TO 52

60 DEALT (L00P3)=0

70 NEXT L00P3

100 FOR L00P1=1 TO 52

110 RAN (LOOPl ) =INT (52+RND ( 1 ) +1 )

120 FOR LaOP2=l TO 51

140 IF RAN (LOOPl )=DEALT(L00P2) THEN 110

150 NEXT L00P2

YOU HAVE 100 DOLLARS.

WHAT !S YOUR BET'^

?50

YOUR HAND TOTALS 18

WITH 0 ACES

THE DEALER HAS 10 + ';*

DO YOU WANT A HIT'?

Fig. 6-2. Blackjack.

160 DEALT (LOOPl ) =RAN(L00P1 )

170 FOR L00P4=1 TO RAN (LOOPl)

180 READ CARD

190 NEXT LOOP4

200 CARD (LOOPl ) =CARD

210 RESTORE

220 NEXT LOOPl

2000 DATA 11,10,10,10,10,9,8,7,6,5,4,3,2

2010 DATA 11,10,10,10,10,9,8,7,6,5,4,3,2

2020 DATA 11,10,10,10,10,9,8,7,6,5,4,3,2

2030 DATA 11,10,10,10,10,9,8,7,6,5,4,3,2

The computer clears the screen, determines that the
number of aces the player an(j the dealer have is zero, and then
checks to see if there are enough cards with which to play. If
there are not. the computer goes to a reshuffling routine at line
1700.

300 GRAPHICS O

303 PA=0:DA=0

305 IF NM>37 THEN 1700

In order for a person to know how much money is available
for betting, the computer shows the amount of money the player
has. then accepts a bet from the player:

310 PR I NT "YOU HAVE "; MONEY;" DOLLARS."

320 PRINT

330 PR I NT "WHAT IS YOUR BET?"

340 INPUT BET

350 IF BET>MONEY THEN 330

360 MONEY=MONEY-BET

The computer gives the player his hand of cards, totals their
value, and then tells the player the value of his cards and how
many aces he has.

:j70 nm=nm+i

:;80 phand=card (nm) +card (nm+1 )

390 if card (nm) ^11 then pa=pa+1

400 IF CARD(NM+1)=11 tHEN PA=PA+1

405 NM=NM+2

410 IF PHAND=21 THEN 1000

420 IF PHAND>21 THEN GOSUB 1100

430 PR I NT "YOUR HAND TOTALS " ; PHAND

440 PRINT"WITH ";PA;'* ACES."

The computer then does the same for the dealer:

500 DHAND=C ARD ( NM ) +CARD ( NM+ 1 )

510 IF CARD (NM) =11 THEN DA=DA+1

520 IF CARD(NM+1)=11 THEN DA=DA+1

525 Nri+2

530 IF DHAND=21 THEN 1200

540 IF DHAND>21 THEN GOSUB 1300

550 PRINTiPRINT

560 PR I NT "THE DEALER HAS:"

570 PRINT CARD<NM);" + ?"

600 PRINTiPRINT

The player is then asked if he wants a hit. If he does, he is
given another card and the value of the hand is checked again. If
he does not want anothercard (i.e. "stand"), the computer will go
to the routine at line 750. Figure 6-2 outlines the dialogue up to
this point.

610 PRINT"DO YOU WANT A HIT?"

620 INPUT A*

630 IF A*<>"Y" THEN 750

640 PHAND=PHAND+CARD < NM )

650 NM=NM+1

660 IF CARD<NM-1)=11 THEN PA=PA+1

670 IF PHAND>21 THEN GOSUB llOO

680 PR I NT "YOUR HAND TOTALS "; PH AND

690 PRINT"WITH •*;PA;" ACES."

700 GOTO 600

If the player decides to stand, the computer will show the
dealers hand and will compare the value of the dealer's hand
with the value of the player's hand, taking appropriate action for
whatever the condition might be. For example, if the dealer
requires a hit. the computer will give him one. If the dealer has a
good hand, the computer will go to the routine at line 1400,
showing that the dealer has won.

750 PRINTsPRINT

760 PR I NT "THE DEALER'S HAND TOTALS " ; DHAND

770 PR I NT "HE HAS ";DA;" ACES."

780 IF PHAND>DHAND THEN 900

790 IF DHAND=PHAND THEN 900

800 IF DHAND >PHAND THEN 14O0

900 IF DHAND >16 THEN 1500

If the computer decides to go to line 91 0, the dealer receives
a hit, checks his hand, then goes back to the previous routine to
see if he requires another hit.

9 1 0 DHAND=DHAND+CARD ( NM )

920 IF CARD<NM)=11 THEN DA=DA+1

930 NM=NM+1

940 IF DHAND >21 THEN GOSUB 1300

950 GOTO 760

In the unlikely event that the player is dealt a blackjack, the
computer informs that player that he has indeed acquired a
21 -point hand, allowing him to win triple his bet money— and the
game.

1000 PR I NT: PR I NT "BLACKJACK"

1010 BET=BET^t3

1020 MONEY^MONEY+BET

1030 GOTO 1600

If the player's cards have a value over 21, the aces are
reduced from 11 to 1 by the computer, as shown below:

1100 IF PA<1 THEN 1400
1110 PA=PA-1
1120 PHAND=PHAND-10
1130 RETURN

Of course, the dealer can also get a blackjack. The routine
below allows for that possibility, and also includes the equivalent
of the "ace routine" shown above.

1200 PR I NT: PR I NT "THE DEALER HAS 21."

1205 IF MONEY=0 THEN 1900

1210 GOTO 1600

13O0 IF DA<1 THEN 1500

1310 DA=DA-1

1320 DHAND=DHAND-10

1330 RETURN

Finally, here are the routines for winning and losing the
game, along with the lines which ask the player if he would like to
play the game again. The last few lines are for the purpose of
"reshuffling" the deck, in case the cards remaining are too few in
number:

1400 PRINT: PR I NT "YOUR HAND TOTALS " ; PHAWn
1410 PR I NT "THE DEALER HAS " ; DHAND
1415 PRINT"YOU LOSE."
1417 IF MONEY=0 THEN 1900
1420 GOTO 1600

1500 PR I NT: PR I NT "YOUR HAND TOTALS " ; PHAND

1510 PR I NT "THE DEALER HAS " ; DHAND

1520 PRINT"YOU WIN!"

1530 M0NEY=M0NEY+BET*2

1600 PRINT: PRINT"DO YOU WANT TO PLAY AGAIN?"

1610 INPUT A*

1620 IF A«="Y" THEN 300

1630 END

1700 PR I NT: PR I NT "SORRY, I MUST RE -SHUFFLE. "

1705 MONEY=MONEY+BET

1710 GOTO 45

RAN(X)

DEALT(X)

CARD(NM)

MONEY

L00P3

L00P1

CARD

LOOP2

L00P4

BET

PHAND

DHAND

Important Variables in Blackjack

Random number to read off a random amount

of data

Used to make sure that the same RAN(X)

has not been used twice

Value of Xth card in shuffled deck

Input to see if player wants to play again

Amount that player has in dollars

Sets DEALT(X) values to zero

Loop for card shuffling routine

Card values read from data

Makes sure that same RAN(X) is not used twice

Used to read data

Number of aces the player has

Number of aces the dealer has

Amount that player bets

Total value of player's hand

Total value of dealers hand

Important Line Numbers in Blackjack

10-45 Initialization

50-70 Clearing DEALT(X)

100-200 Entire shuffling routine

110 Get random value

120-150 Makes sure value has not been used before

160 Stores random value for use in 120-150

1 70-1 90 READS random number of card values

200 Gets value of card

305 Goes to line 1700 if there are not enough

cards with which to play
31 0-340 Gets players bet
350 Makes sure the player doesn't bet more than

he has
370-440 Gives player his hand, counts number of aces,

totals its value, see if it's over 21 or 21 even
500-570 Does same for the dealer

600-630 Sees if player wants a hit

640-690 Gives player a hit, checks value of hand

700 uoes to ask if player wants a hit again

750-900 Sees if dealer needs a hit, or if he has 17or over

910-950 Gives dealer a hit, checks his hand, goes back

to see if he needs another hit
1 000-1 030 Tells player he got blackjack, asks if he wants to

play again after adding to his money
1 1 00-1 1 30 This routine checks to see if the player has any

aces since he has over 21 . Aces are

therefore changed from 1 1 to 1
1 200-1 21 0 Informs the player that the dealer dealt himself

21 , sees if player lost all of his money or not
1300-1330 Ace routine for the dealer
1400-1420 Informs the player that he has lost
1 500-1 530 Informs the player that he has won and adds

his bet to the money he already has
1600-1620 Sees if player wants to play again.

Now that we have taken a look at just about every type of
program we can make on the ATARI home computer, and are
knowledgeable in the BASIC language and how it can be
utilized, we can complete our learning and programming experi-
ence. Let's see how you can make your own ideas for your own
programs and then develop them into actual, working pieces of
software.

Chapter 7

Creating Your Own Programs

Up to now you have been entering and using the programs in this
book, discovering the various keywords used in creating pro-
grams, and finding out new uses for your computer. Along the
way. you have probably devised some program ideas of your
own. and you might have modified the programs in this book for
your own purposes or experimentation. If you have, this is an
excellent first step to becoming "your own programmer." If you
havent. you might want to try to develop your programming skills
now by reviewing some of the programs you have typed in and
making some changes, no matter how insignificant.

The main point is that helping you acquire the ability to
create your own programs is one of the main purposes of this
book. You should learn at least some of the BASIC keywords of
the ATARI and know the proper way to put the words together to
make a usable program. More importantly, you should learn the
technique behind creating a program. This last aspect has not
yet been covered, so we will explore it in this final chapter.

THE USEFUL COMPUTER

Because one of the most important aspects of creating a
program is coming up with an original program idea, we should
first look at the different types of programs so you can find an
idea which might fit into one of these types. Reading about these

101

various kinds of programs will probably make it easier for you to
develop an idea for a program.

The first (and probably most obvious) type of program for
the 600XL or 800XL computer system is entertainment
software. Their high-resolution graphics, excellent sounds, and
relatively large memory make them excellent machines on
which to play games. There have already been a wide variety of
computer games developed for the ATARI home computers,
and here are some types that have already come into existence
for the 600XL and 800XL.

Games of Chance. These might be called "gambling games,"
since they involve themes that would usually be found in Las
Vegas. 'One-Armed Bandit" (a slot machine), Blackjack, and
Keno are just a few. Computers are excellent for playing card
games and games of chance, especially the 600XL or 800XL
with color graphics (useful for displaying cards, slot machines, or
dice), sounds (for indicating winning or losing), and large mem-
ory (for storing a great deal of information).

Adventures. An adventure is a game in which you play the
part of a person in a strange situation (such as on a deserted
island, on a faraway planet, or in a haunted house) who must use
skill and luck to retrieve treasures, stay alive, or (usually) both.
Adventures are enjoyable because they involve strategy and wit,
and they can put you in a fantasy world which only your computer
and your imagination can produce.

Arcade Games. These are certainly the most popular of all
kinds of games, since they combine exciting graphics, sounds,
and fast action to produce a game requiring fast reflexes— but
little intelligence. One look at any magazine which includes the
ATARI home computers in its subject matter will show you that
there are many arcade gamescurrently available forthe ATARI.

Board Games. Some games (like 'Xife" from Milton Bradley
and "Monopoly" from Parker Brothers) commonly played on
boards can be adapted for use on the computer. In fact, some
games exist for other computers which let the computer play
against you in a board game.

Logic Games. Games which require a lot of logical thinking
(like ''Mastermind, ' which requires you to pick out a pattern of
four colored pegs) are popular on computers, since program-
mers and other people who enjoy computers are usually logical
folks who enjoy using their mind to solve problems.

This covers most of the different kinds of games which are

102

available for the 600XL and 800XL computer systems. Another
type of software which give the 600XL or 800XL a useful appli-
cation besides entertainment is educational software.

Learning from a computer is an extremely exciting possibil-
ity. Children (and adults) can discover foreign languages, ad-
vanced mathematics, and excellent spelling habits by utilizing a
computer able to show them rules, test them, quiz them with
repetitive questions and have an infinite amount of patience and
encouragement. Human teachers certainly can do a lot better
teaching some subjects than computers can, but for repetitive
teaching or education which doesn't require a lot of creativity or
customized training by the educator, computers are excellent for
instructing people in a wide variety of subjects.

There are several types of programs available today which
can help many young people and adults in learning about math,
science, spelling, or practically any other subject.

Computer Literacy. One of the best things that computers like
the 600XL or 800XL can teach is. naturally, how to work with
computers. Programs can teach how to use the BASIC lan-
guage, how to use the keyboard, what the different parts of a
computer are, how to use a word processor, and what program-
ming is involved in producing graphics and sounds. As I have
mentioned before, experience is a much better teacher than a
book (including this one), or a program, but you need to learn the
basic information somewhere— which is why a book and/or a
program is often helpful when you are learning about your com-
puter.

SAT Instruction. The infamous Scholastic Aptitude Test
(SAT) is one of the most important criteha used by colleges
considering high school students for admittance. Because of
this, the SAT is a matter of great importance to many young
people. This is why programs which assist young people with the
SAT tend to be very popular. In addition, computers can teach
other tests, such as the PSAT, Achievement Tests, or tests at
the college level.

Drilling and Practice. The most popular kind of educational
program is the "drilling and practice" program, which teaches a
person something through repeated instruction and testing. The
subject could be mathematics (addition, subtraction, multiplica-
tion, geometry), science (formulae, science in history), or any
other subject you can imagine.

Educational software is commonly used in the home, but

103

some schools are starting to purchase these types of programs
as supplements to their teaching curricula. At home, another
useful type of software available for the 600XL or 800XL is the
home finance program. Keeping track of financial records is an
excellent application for computers; the 600XL or 800XL is able
to help you plan your budgets, balance your checkbook, make
investments, and manage your whole "portfolio" and finances
for your household. Being a computer, the 600XL or 800XL is a
"whiz at math" with a significant amount of memory; the pro-
grams using these qualities to keep track of home finances will
be very useful indeed.

Even though the 600XL or BOOXL can be used with the
popular AtariWriter word processor from Atari, Inc., there are
additional word processing programs available, which you will
see advertised in most general computer magazines. They may
have some extra features you might find desirable that Atari-
Writer doesn't have. Besides the other WP programs, there are
"supplemental" programs made for AtariWriter and other word
processors which check the spelling of your documents. You
can then use your word processor for form letters and other
business-related needs without having to worry about misspell-
ings.

Finally, another application made possible through
software development for the 600XL and BOOXL Is the use of
other computer languages. Currently the 600XL and 800XL not
only let a user work with BASIC, but also have the software to
support other languages (such as machine language and
LOGO). You can learn more about the languages of computers
(for there are many of them) and find ways in which programs
can operate faster and more efficiently.

The demand for software with the 600XL or 800XL has been
very high, but there are always more programs or applications
you can create (by making your own programs) that people will
find useful. Here is where a great opportunity for you comes in.
You can make software for the 600XL or BOOXL and sell it to
other people. You could be one of the "suppliers of software" for
the many who will be wanting it. On the other hand, you might
want to program the software yourself and, instead of selling it
yourself, find a software publisher to mass produce and sell it for
you. This is exactly the subject of the next section, in which we'll
explore ways to create programs with your machine — and
perhaps later make money with your 600XL or 800XL computer.

104

GETTING AND DEVELOPING THE IDEA

I have written a large number of nationally marketed pro-
grams myself, so people sometimes ask me, "What is the hard-
est part about making a program?" I reply to their surprise,
"Getting the idea.'' This might not be an absolutely true state-
ment, since debugging a program is also extremely difficult, but I
do find that getting and developing an Idea for a program is often
one of the most difficult parts of programming.

When you are trying to think of an idea for a program, you
should think of who is going to be using it. Naturally, if it is for your
own use, you should make only what you need. If you are going
to be making a program for other people to use, however, you'll
probably want to think of an original idea. This can be very
difficult indeed, since there are already a great many programs
available on the market. The best way to create an original idea
foraprogram. though, istothinkofaneed which someone might
want "filled ' by a computer. Here are a few types of people,
along with a sample program each might find useful:

POTENTIAL USER USEFUL PROGRAM IDEA

Teachers Software to keep track of grades

Church Program to keep records of

Administrators donations

Students Programs to help with SAT test

Small Businessman Inventory records program

Audiophile Program to keep track of records

Remember also, especially if you are a young person who
enjoys video games, that games are not the only programs you
can create for the 600XL or 800XL. Some kinds of programs you
could try to Include word processors, communications programs,
utility (programmer helper) programs, and almost anything else
you can devise. Just keep this in mnd.the more original, useful,
and needed your program is, the more popular it will be.

If you are going to create a program simply for your own
purposes, then teach yourself more about computers, think of
the various features your computer possesses and how to
exploit them, and experiment with BASIC keywords and
techniques you have not used before. You can learn how to
program like a professional, since professionals build their

105

knowledge on their own experience.

The best-selling programs are attractive to large numbers of
people; however, you might want to make a program for a more
narrow group of people— like your family, your friends, or stu-
dents who attend a nearby school.

Let's assume that we need to create a program for an
introductory computer class. In order to get the idea for this
program, we think about what would impress or interest a class
about computers. One idea that comes to mind is a short, simple
program which lets the computer introduce Itself, gets the user's
name, and then greets the user by name. This is, of course, a
very basic program, but for this example it will suffice.

At this point, we need to develop the program idea. De-
velopment involves the expans/on of your idea, paying attention
to minute details, and sometimes drawing a flowchart of your
program. Not all of the specifics you write down about your
program may make it into the final product. You should have
some flexibility in your programming, but you should try to stick
to your original ideas as much as possible.

As far as flowcharting is concerned, we aren^t going to use a
flowchart in our programming example because the program is
too short and simple to require one. More complex programs do
require flowcharts, but you can probably get away without them
until you are making programs larger than, say, forty lines long.
Still, flowcharting is good logical exercise and an excellent habit
to aquire.

A flowchart is basically a picture of a program's "flow"— the
sequence of processes by which it works. A flowchart shows,
with words and shapes, the main parts of a program and how
they interact with one another. There are five main symbols,
shown in Fig. 7-1, which make up most flowcharts.

START/STOP oval. This indicates the beginning and end of a
program.

Rectangle. Most of a program's functions are represented
within a rectangle, which represents unconditional, "process"
action. Such statements as PRINT, READ, clear the screen, and
variable assignments can be represented within the rectangle,
along with most other statements not including INPUT END
and IF-THEN.

Diamond. This figure represents conditional action, i.e., de-
cisions made by the computer. IF-THEN statements are con-
tained within diamonds. There are two arrows coming out of the

106

STOP/START
OVAL

PROCEDURE
RECTANGLE

DECISION
DIAMOND

INPUT
PARALLELOGRAM

FLOW
ARROWS

Fig. 7-1. Flowchart symbols.

diamond rather than just one, as with other statements. One
arrow represents where program execution will "flow" If a condi-
tion turns out to be false, while another arrow is for a true
condition.

Parallelogram. For statements involving INPUT, use this
figure.

107

Arrows. The arrows in a flowchart represent the "flow" of a
program. Execution can travel only in the direction of the arrow.

Another important part in developing a program is forming
the essential details relating to the program. For example, some
of the details relating to our simple example in this chapter
include:

1) The program will have to introduce itself to the person.
This will involve clearing the screen and PRINTing sev-
eral lines.

2) When the computer asks the user's name, an INPUT
statement will be required to get the input.

3) Once the computer knows the person's name, it will
have to use the person's name (now represented by a
variable) along with some PRINT statements to greet
that person.

If you are making a more complex program, such as one
involving business or word processing, your "details" can be far
more general, such as, "The computer will have to be able to
search for words within a document, so I must program it to store
a 'search string' and look for it within the document," or, "In the
middle of the program, the values will have to be stored on the
disk to insure they are not lost." As far as our program is con-
cerned, however, we have created an idea for it and we know the
fundamentals parts of the program which must be coded.

PROGRAMMING

The actual programming will be a lot easier if you have a
flowchart at hand when you are making a large program. What-
ever the size of your project, you should have the details of the
program written on paper, as well as a good idea of what
keywords and techniques you'll be using In the program. If you
are making a large program, try breaking it down into smaller
sections, and program these one at a time. In addition, try
checking each of these individual sections as you go along to
save yourself time in the debugging process. Getting rid of
problems now will be much easier than searching through your
entire program later for the bugs. Last, be creative, innovative,
and as efficient as possible when you are programming, since
these three elements are essential to creating a quality program.

108

Our "simple sample" won't be hard to make. First of all, we
need to construct the computer's introduction as follows:

10 REN INTRODUCTORY CLASS PROGRAM

20 PRINT"HI THERE. I AM AN ATARI COMPUTER. I AM NEW"

30 PR I NT "AROUND HERE, SO I WAS HOPING YOU COULD TELL"

The first line is a REMark to show the purpose of the
program. In lines 20 and 30, the computer introduces itself. At
this point, we can make the part which allows INPUT from the
user so that he can identify himself.

40 INPUT "WHAT IZ YOUR NAME*';NS

Finally, the computer greets the person by name:

50 PRINT"HELL0 THERE, ":PRINT N*

Don^t be alarmed if you see a few errors in the program
above. This is intentional since we need to see how we go about
debugging a program in the next section.

DEBUGGING

The most grueling and boring step of making a program, as
well as the most exciting and rewarding, is the debugging pro-
cess. It is boring because you have to search through your
program to find any problems or potential errors, and it is exciting
because you will feel a surge of victory every time you conquer a
bug. Looking for those elusive bugs involves testing every pos-
sible input the user could give the computer, making the program
do everything it is capable of doing, and trying your best to make
the program fail. You will probably be somewhat cautious while
testing your program, since nobody likes to find more problems
to solve. Do not simply give up, however, assuming that you
have conquered all the bugs. You must give your program a real
workout to assure top performance. Spend all the time you can
with it. since there may still be one problem which a user could
discover later. This could be rather embarassing.

Our program has a few problems in it. First of all, it should do
the following:

HI THERE- I AM AN ATARI COMPUTER. I AM NEW

109

AROUND HERE, SO I WAS HOPING YOU COULD TELL
ME: WHAT IS YOUR NAME? TIM KNIGHT
HELLO THERE, TIM KNIGHT

However, if you run the program, you will find it does this:

HI THERE. I AM AN ATARI COMPUTER, I AM NEW
AROUND HERE, SO I WAS HOPING YOU COULD TELL
WHAT IZ YOUR NAME? TIM KNIGHT
HELLO THERE,
TIM KNIGHT

As you can tell, we have a few mistakes which need cor-
recting. To begin with, the third line of text is not right. Change
the WHAT 12 YOUR NAME to ME: WHAT IS YOUR NAME. Also,
the name is phnted on the second line rather than on the same
line as HELLO THERE. To correct this, you can either put a
semicolon after the end quote following HELLO THERE, or you
can simply eliminate the second PRINT statement in line 50. The
line would then read PRINT'HELLO THERE, "N$.

This program wasn't very difficult to debug since it was so
small, but most programs are rather tedious and mind-boggling
when you are debugging them. Remember these important
things when you are debugging any program:

1 ) For a program that requires input, try inputting anything
you can imagine. If the program wants numbers, give it
letters, names, symbols, and anything else you can
type. If a computer wants you to use the "6" key to move
the cursor right, keep pressing it to see if an error will
occurwhen the cursortriesto move off the boundariesof
the screen.

2) Try every incorrect method of using a program to make
sure that it is foolproof.

3) Get other people to use your program. They are much
better judges of it than you are. They can also provide
helpful constructive criticism and comments on the pro-
gram, and can alert you to problems existing in the
software.

110

Once you have finished programming and debugging a
piece of software, you should write some documentation (in-
structions) for it. Simply type out the basic facts a person needs
to know to use your program, and mention some ways in which
the program can be used. If you are doing the program for a
software company, you should make the documentation itself an
excellent work. Since you probably won't be doing that for a
while, there's no need yet to concentrate on writing anything but
the essentials.

MAKING PROGRAMS AND MONEY WITH YOUR ATARI

Many people (including a large number of young people)
have made something of a business out of writing software for
computers. In fact, being a professional programmer can be a
very profitable job, even if you just work out of your home
producing one or two programs a year. Until now the software
market has been pretty well saturated for most computers, but
newly introduced machines offer an excellent opportunity for
programmers to write more software for a variety of applications.
This opportunity exists with the 600XL or 800XL, and you could
make yourself quite a lot of money with your computer through
software development.

There are a number of ways to make money with computers
(see Fig. 7-2). Writing software reviews for computer mag-
azines, writing articles, creating computer-related books,
teaching computer classes, or serving as a computer consultant
to a person or a business are just a few. However, the particular
way of making money with your600XLor800XLI am discussing
now— making software— probably offers more rewards and ex-
citementthananyothercomputer-relatedbusinessopportunity.

The profits of making software come in a vahety of forms.
First of all, writing a program will inevitably put you in the position
of being an ''exterminator," since you'll have to seek out and
destroy all the bugs in the program you create. The profit from
this, though, is the good feeling you have when you finally
remove a bug from your program. Until you actually find and fix a
difficult mistake in one of your own creations, you won't be able
to understand the feeling of accomplishment your achievement
can give you. After you have, you'll want to keep searching and
stamping out those bugs, no matter how frustrating and time-
consuming they might be.

111

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112

Another profit which comes from making programs, natur-
ally, is the money you receive. If you give your program to a
software publisher, which is probably the best decision, you will
receive a certain royalty for every copy of your program that is
sold. For instance, assume you have made a great home finance
manager program that is being sold for $30 per copy. Assume
again that you receive 25 percent of the wholesale price of your
program (about $15), making your royalty $3.75. If 10,000
600XL or 800XL users purchase your program, this would result
in a profit of $37,500 for you— which is an excellent compensa-
tion for your work as a programmer. Of course, you shouldn't
always expect royalties this high, but some people have made
millions of dollars on their programs. (One person I know made a
million with one arcade game.) Many other programmers have
six-figure incomes for their work. The more popular the 600XLor
800XL becomes, and the better your program is (in addition to
how good your software publisher is), the more money you are
likely to receive for your program.

The method by which you create a program was discussed
earlier in this book, but here are a few more pieces of advice
when creating your program for the software market;

1 ) Make the documentation as complete and easy to un-
derstand as possible. This will assist the novice 600XL
or 800XL user in utilizing your program.

2) Test the program as thoroughly as you can before
sending it to a software publisher. Have other people
use your program, and get their constructive criticism of
how your program can be improved, what problems
exist in the program, and what can be done with the
documentation to make the program easier to use as
soon as a person purchases it.

3) When thinking up your original idea for the program,
make it as original as possible and as attractive to a
buyer as you can. Imagine yourself in the position of
someone who is looking at a software package and has
not tried the program, but who wants to find something
that is entertaining, educational, or very useful.

The important step now is to get in contact with the software
publishers who interest you, see if they like your idea for a

113

program, and then get to work on the actual software. Develop it
and have the publisher market it for you,

THE FUTURE OF COMPUTERS

Since computers have changed so much over the past few
years, it's difficult to say what will be happening to the ATARI
600XL, ATARI 800XL other home computers, and the field of
high technology in general. However, I do have some sugges-
tions as to what will probably be occurring over the next couple of
years in these areas. These predictions may prove useful to you
in some way.

Firstof all, computers aren'tlikely todrop inpricemuch more
than they already have. When personal computers were intro-
duced, they cost $2,000 or more, but a few years later the price
fell to $500, $300, and then to $1 00 or less. Unfortunately, since
the price fell so much, the cheapest personal computers became
poorly constructed toys. The price increased, along with the
quality, back to $200. At this price, personal computers were
affordable and still of a quality high enough to satisfy the con-
sumer. Prices stayed around $200 to $700 for home computers,
but the features began to increase. The result, up to now, has
been the 600XL or 800XL computer— low in price, but with a lot
of fantastic features which would have cost you thousands of
dollars a few years ago. This trend is likely to continue. You'll
probably see more inexpensive and feature-packed computers
appearing, in addition to low-cost extra peripherals and software
being made available for the 600XL or 800XL.

Another important trend is that software is getting easier to
use and more practical. This will result in computers being made
even more useful than they already are, with programs being
written in such easy to understand terms that even the novice will
be able to utilize all kinds of software. A good example is Atari-
Writer, which is a program made simple to use by extensive
prompting from the computer.

Finally, computers will be expanding into what I like to call
probots, which is short for personal robots (Fig. 7-3). Personal
robots are an extension of the home computer, with all the
powers of a computer like the 600XL or 800XL, but with the
additional utility of motion and the power to manipulate objects.
Soon your 600XL or 800XL computer may be able to control a
personal robot and make it guard your house, watch for and
extinguish fires, and entertain guests. The personal robotics

114

Fig. 7-3. A probot of the future.

revolution is likely to be as influential as the personal computer
revolution, so it will be exciting to see what developments occur
in that new field.

Your 600XL or 800XL computer is a powerful tool and a
wonderful extension of yourown mind. Use it like atool, and let it
entertain you, make you more efficient, and keep your records in
order. The personal computer revolution has brought a lot of
changes, including this inexpensive and powerful system called
the 600XL or 800XL. Learn to program it well through your own
experiences, and use it as often as you can for as many varied
applications as you can find— to discover how useful and enjoy-
able the ATARI 600XL or 800XL computer can truly be.

115

Glossary

Array— A set of variables set apart from one another by numeri-
cal subscripts. Examples: A(1 ), B$(20), C(50). Before you use
an array, you must set it up with the DIM statement.

ASCII— A standardized coding system which assigns corres-
ponding code numbers to letters, numbers, and symbols.

Binary— The number system computers use, composed of zeros
and ones.

Bit— The smallest unit of information the ATARI can hold. Bit is
short for binary digit, since a bit can be either one or zero.

Bug— A problem in a program.

Byte— The basic unit of information in the computer. A byte is a
unit of memory equal to eight bits.

Command— A word you give to the ATARI computer so that it will
carry out some function.

Disk— A piece of Mylar plastic on which you can permanently
store programs, data, and other kinds of information.

116

Disk drive— The device you use to store and retrieve programs
and information. The disk drive is faster and more efficient
than the tape recorder.

Display— The television set, monitor, screen, video display, or
whatever you want to call the device that shows you the
information of the computer on a cathode-ray tube.

Edit— To modify or change information.

Error— A mistake in a program, or in one of your commands to
the computer.

Execute— To begin running (using) a program.

Graphics— Visual information in the form of pictures such as bar
graphs, spaceships in a game, or a piece of "computer art"
formed by the ATARI'S advanced high-resolution graphics.
The ATARI can also support low-resolution graphics, which
aren't as well-defined but can be displayed in a wider variety
of colors.

Hardware— The electronic components of a computer system,
such as the printer, the keyboard, the microprocessor, and so
on. Hardware can be physically damaged if mistreated, so
treat your ATARI with care.

Integer— A whole number without a decimal part. 5, 2, 6, and
2,034 are integers, while 2.53245 is not.

Joystick- The device usually used in games to move your "man"
around the screen. Joysticks are attached to the keyboard
and can be used to indicate direction. Because of this, they
are commonly used in arcade-type games.

K— The name given to designate a certain amount of memory.
One K is equal to 1,024 bytes. The ATARI 600XL has 16K,
which equals 16,384 bytes of memory.

Keyboard— The part of the ATARI Computer System on which
you can type information for the computer to use.

117

Machine Language— An extremely fast means by which the com-
puter can carry out programs, since machine language is the
actual "language of the computer"— as opposed to BASIC,
which must be interpreted by the computer and translated by
the ATARI into its own machine language.

Memory— The computer's information storage center.

Peripheral— An extra device for your computer, such as a printer,
a modem, a disk drive, or a joystick.

Printer— The device which gives you a "hardcopy" (printed ver-
sion) of information, such as a letter, a listing of a program, or
an essay.

Reserved word— A word which can be used only by the ATARI.
You cannot use it for variable names or uses other than giving
the ATARI commands. For example, you couldn't let a vari-
able named LIST equal 1 0 since the name LIST is used by the
ATARI to list out programs. It is a reserved word.

Software— The programs the ATARI uses. When you turn the
computer off, any software (programs) in the computer will be
erased. In order to save programs for later use, store them
onto a disk or a cassette tape.

String— A series of characters and/or symbols assigned to a
variable called astring. String variables are represented by a
dollar sign ($) following them. A$, Y1 $, and UU$ are all string
variables, which can equal such things as "123," "YOU
THERE," and "ATARI."

Text— Words and letters you can understand, such as this sen-
tence.

118

Index

BASIC statements and functions are indexed by first usage in a pro-
gram.

Adventure. 102

Assignment (implied LET) statement,

9
ATARI, voices of, 12

Basic Skills Check-Up program. 52
Blackjack program. 92

Calculator program, 49
CLOG function. 52
Colorbar program, 71
COLOR statement. 15
Computer literacy, 103
COS function, 52

DATA statement. 10
Debugging, 109
DEG statement, 50
DIM statement. 21
Documentation, 113
Drawer program, 77
DRAWTO statement. 15

END statement, 22

Flowchart, 106
Flowchart symbols, 107
FOR-TO-NEXT statement, 8
French Tutor program. 35

Games, arcade, 102
Games, board, 102
Games, logic, 102
Games of chance. 102
Geometry program, 56
GOSUB statement. 9
GOTO statement, 2
GRAPHICS statement. 7
Graph program. 80
Greater-than operator, 14
Guess My Number program, 85

High resolution. 71
History Quiz program. 27
Hue. 71

Idea development, 105
IF . . . THEN statement, 9
INPUT statement, 2
INT function, 19

119

Length Converter program. 62
Less-than operator, 14
LOGO. 104
Low resolution, 69
Luminance, 71

Machine language, 104
Making money, 1 1 1
Metric system, 62
Musical notation, 21
Music Creator program, 20

NEW command, v
Notation, musical, 21

GOTO statement, 8

REM statement, 2
RESTORE statement, 7
RETURN statement, 10
RND function, 19

Scholastic Aptitude Test (SAT), 103

SETCOLOR statement, 72

Shapes program, 74

Simon Says program, 88

SIN function. 52

Software, educational, 103

Software, entertainment, 102

Song Library program, 7

Sound Effects Library program, 17

Sound Maker program, 12

SOUND statement, 8

Spelling Tester program, 32

SQR function, 51

States and Capitals program, 40

PEEK function, 13
PLOT statement, 15
POKE statement, 13
POSITION statement,
PRINT statement, 2
Probot. 114
Programming, 108
Publishers, software.

READ statement. 8

114

Tangent (computed), 52
Testing, program, 113
Time-delay loop. 18
Timer, memory location of. 53

Unequal-to operator, 22

VAL function, 22

120

Edited by Stephen Moore

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